Public Water Systems

Public Water Systems

Providing safe drinking water is a partnership that involves EPA, the states, tribes, water systems, and water system operators. The public drinking water systems regulated by EPA and delegated states and tribes provide drinking water to 90 percent of Americans.

A public water system provides water for human consumption through pipes or other constructed conveyances to at least 15 service connections or serves an average of at least 25 people for at least 60 days a year.  A public water system may be publicly or privately owned.

EPA data reports that there are over 148,000 public water systems provide drinking water to approximately 90% of the population or over 283 million Americans. The other 10% have private wells, which are not federally regulated.

The EPA classifies these water systems according to the number of people they serve, the source of their water, and whether they serve the same customers year-round or on an occasional basis.

Classifications:

EPA has defined three types of public water systems:

• Community Water System (CWS): A public water system that supplies water to the same population year-round.
   
• Non-Transient Non-Community Water System (NTNCWS): A public water system that regularly supplies water to at least 25 of the same people at least six months per year. Some examples are schools, factories, office buildings, and hospitals which have their own water systems.
   
• Transient Non-Community Water System (TNCWS): A public water system that provides water in a place such as a gas station or campground where people do not remain for long periods of time.

EPA sets legal limits on over 90 contaminants in drinking water. The legal limit for a contaminant reflects the level that protects human health and that water systems can achieve using the best available technology. EPA rules also set water-testing schedules and methods that water systems must follow.

The Safe Drinking Water Act (SDWA) gives individual states the opportunity to set and enforce their own drinking water standards if the standards are at a minimum as stringent as EPA’s national standards.

Unregulated contaminants

EPA uses the Unregulated Contaminant Monitoring Program to collect data for contaminants suspected to be present in drinking water, but that do not have health-based standards set under the SDWA. Every five years EPA reviews the list of contaminants, largely based on the Contaminant Candidate List.

The Safe Drinking Water Act

The overall purpose of the Safe Drinking Water Act (SDWA) is to assure that water supply systems serving the public meet certain minimum national standards. The act directs the EPA to establish a regulatory program and to enforce it in such a way as to provide for uniform safety and quality of drinking water in the United States. Specifically, the act requires EPA to do the following:

(1) Set standards for drinking water specifying maximum permissible levels of contamination and minimum monitoring frequencies.

(2) Protect sole or principal sources of drinking water from contamination by federally assisted projects.

(3) Protect underground drinking water sources from contamination by underground injection.

(4) Establish regulatory programs for assuring compliance with the standards.

(5) Ensure proper implementation of the regulatory program through oversight and technical assistance to the states or, if necessary, through direct implementation.

(6) Provide financial assistance to the states in their implementation of programs

(7) Gather pertinent information pertaining to drinking water sources and supplies

The SDWA differs substantially from previous Federal legislation in that it is directly applicable to all public water systems.

The SDWA is the most important water industry federal law. It establishes 4 uniform national safety and quality standards for drinking water including physical, chemical, bacteriological, and radiological standards.

The National Primary Drinking Water Regulations

a. General. These regulations specify the maximum permissible levels of contaminants that may be present in drinking water. While their principal purpose is to protect the public health, these regulations authorize a maximum contaminant level (MCL) to be set for a given substance, or group of related substances, even though no direct linkage to public health has been conclusively shown. The USEPA Administrator is empowered by the SDWA to consider economic feasibility as well as public health in establishing MCLs. The SDWA allows the Administrator of USEPA to establish treatment methodology criteria in order to provide general protection against a contaminant or group of contaminants without specifying any MCL

b. Nomenclature. Several terms used in the SDWA and the DWP are specifically defined therein. Those that are especially pertinent are defined below.

(1) Contaminant. A contaminant is any physical, chemical, biological, or radiological substance or matter in water.

(2) Maximum contaminant level (MCL). The MCL is the maximum permissible level of a contaminant in water delivered to the free-flowing outlet of the ultimate user of a public water system, except in the case of turbidity where maximum permissible level is measured at the point of entry to the distribution system. Contaminants added to the water under circumstances controlled by the user, except those resulting from corrosion of piping and plumbing caused by water quality, are excluded from this definition.

(3) Public water system. A public water system is a system for the provision to the public of piped water for human consumption, if such a system has at least 15 service connections or regularly serves an average of at least 25 individuals at least 60 days out of the year. Collection, pretreatment storage, treatment, storage, and distribution facilities are included in this definition. A public water system may be further classified as a “community” or “noncommunity” water system.

TOTAL COLIFORM RULE

The Total Coliform Rule (TCR), a National Primary Drinking Water Regulation (NPDWR), was published in 1989 and became effective in 1990. The rule sets a health goal (Maximum Contaminant Level Goal (MCLG)) and legal limits (Maximum Contaminant Levels, MCLs)) for the presence of total coliforms in drinking water.

The Environmental Protection Agency (EPA) published the Revised Total Coliform Rule (RTCR) in the Federal Register (FR) in February 2013 (78 FR 10269) and minor corrections in February 2014 (79 FR 10665). The RTCR is the revision to the 1989 Total Coliform Rule (TCR) and is intended to improve public health protection. All public water systems (PWSs), except aircraft PWSs subject to the Aircraft Drinking Water Rule (ADWR) (40 CFR 141 Subpart X), must comply with the RTCR starting April 2016, or an earlier state effective date.

Total coliforms are a group of related bacteria that are, with few exceptions, not harmful to humans. This is very important to note. The EPA considers total coliforms a useful indicator of other pathogens for drinking water. Total coliforms are used to determine the adequacy of water treatment and the integrity of the distribution system.

Key provisions of the RTCR include:

1. Setting a maximum contaminant level goal (MCLG) and maximum contaminant level (MCL) for E. coli for protection against potential fecal contamination.
2. Setting a total coliform treatment technique (TT) requirement.
3. Requirements for monitoring total coliforms and E. coli according to a sample siting plan and schedule specific to the PWS.
4. Provisions allowing PWSs to transition to the RTCR using their existing Total Coliform Rule(TCR) monitoring frequency, including PWSs on reduced monitoring under the existing TCR.
5. Requirements for seasonal systems (such as, Non-Community Water Systems not operated on a year-round basis) to monitor and certify the completion of a state-approved start-up procedure.
6. Requirements for assessments and corrective action when monitoring results show that PWSs may be vulnerable to contamination.
7. Public notification (PN) requirements for violations.
8. Specific language for CWSs to include in their Consumer Confidence Reports (CCRs) when they must conduct an assessment or if they incur an E. coli MCL violation.

REVISED TOTAL COLIFORM RULE

Overview of the Rule
Revised Total Coliform Rule (RTCR) 78 FR 10269, February 2013, Vol. 78, No. 30

Purpose: Increase public health protection through the reduction of potential pathways of entry for fecal contamination into distribution systems.

General Description
The rule establishes a maximum contaminant level (MCL) for E. coli and uses E. coli and total coliforms to initiate a find and fix approach to address fecal contamination that could enter into the distribution system. It requires public water systems (PWSs) to perform assessments to identify sanitary defects and subsequently take action to correct them.

The Total Coliform Rule applies to all Public Water Systems.

Implementation of the Total Coliform Rule will result in:

1. A decrease in the pathways by which fecal contamination can enter the drinking water distribution system.
2. Reduction in fecal contamination should reduce the potential risk from all waterborne pathogens including bacteria, viruses, parasitic protozoa, and their associated illnesses.

Requirements:

1. Public Water Systems must develop a written sample siting plan that identifies the system’s sample collection schedule and all sample sites, including sites for routine and repeat monitoring.
2. PWSs monitoring quarterly or annually must also identify additional routine monitoring sites in their sample siting plans.
3. Sample siting plans are subject to state review and revision.

Routine Sampling Requirements

1. Total coliform samples must be collected by Public Water Systems at sites which are representative of water quality throughout the distribution system according to a written sample siting plan subject to state review and revision.
2. For Public Water Systems collecting more than one sample per month, collect total coliform samples at regular intervals throughout the month, except that ground water systems serving 4,900 or fewer people may collect all required samples on a single day if the samples are taken from different sites.

Repeat Sampling Requirements
Within 24 hours of learning of a Total Coliform positive routine sample result, at least 3 repeat samples must be collected and analyzed for total coliform:

1. One repeat sample must be collected from the same tap as the original sample.
2. One repeat sample must be collected from within five service connections upstream.
3. One repeat sample must be collected from within five service connections downstream.
4. The PWS may propose alternative repeat monitoring locations that are expected to better represent pathways of contamination into the distribution system.

If one or more repeat sample is Total Coliform Positive:

1. The TC+ sample must be analyzed for the presence of E. coli.
2. If any repeat TC+ sample is also EC+, then the EC+ sample result must be reported to the state by the end of the day that the PWS is notified.
3. The PWS must collect another set of repeat samples, unless an assessment has been triggered and the PWS has notified the state.

Routine Sampling Requirements

1. Each total coliform-positive (TC+) routine sample must be tested for the presence of E. coli.
2. If any coliform-positive (TC+) sample is also E. coli-positive (EC+), then the EC+ sample result must be reported to the state by the end of the day that the PWS is notified.
3. If any routine sample is TC+, repeat samples are required.
4. Public Water Systems on quarterly or annual monitoring must take a minimum of three additional routine samples (known as additional routine monitoring) the month following a TC+ routine or repeat sample.
5. Reduced monitoring may be available for Public Water Systems using only ground water and serving 1,000 or fewer persons that meet certain additional Public Water System criteria.

Assessments and Corrective Action
The RTCR requires PWSs that have an indication of coliform contamination (e.g., as a result of TC+ samples, E. coli MCL violations, performance failure) to assess the problem and take corrective action. Two levels of assessments exist (i.e., Level 1 and Level 2) based on the severity or frequency of the problem.

Purpose of Level 1 and Level 2 Assessments
To find sanitary defects at the Public Water System including:

1. Sanitary defects that could provide a pathway of entry for microbial contamination
2. Sanitary defects that indicate failure (existing or potential) of protective barriers against microbial contamination.

Deadline for Completing Corrective Actions
When sanitary defects are identified during a Level 1 or Level 2 Assessment, they should be corrected as soon as possible to protect public health. The Public Water System must complete corrective actions by one of the following timeframes:

1. No later than the time the assessment form is submitted to the state, which must be within 30 days of triggering the assessment, or
2. Within state-approved timeframe which was proposed in the assessment form.

Level 1 Assessments
Conducting Level 1 Assessments

1. Performed by the PWS owner or operator each time a Level 1 Assessment is triggered.
2. Upon trigger of a Level 1 Assessment, the Level 1 Assessment form must be submitted within 30 days to the state.

Level 1 Assessment Triggers
Level 1 Assessment is triggered if any one of the following occurs:

1. A Public Water System collecting fewer than 40 samples per month has 2 or more TC+ routine/ repeat samples in the same month.
2. A PWS collecting at least 40 samples per month has greater than 5.0 percent of the routine/repeat samples in the same month that are TC+.
3. A PWS fails to take every required repeat sample after any single TC+ sample.

Level 2 Assessments
Conducting Level 2 Assessments
Performed by the state or state-approved entity each time a Level 2 Assessment is triggered.

1. The Public Water System is responsible for ensuring that the Level 2 Assessment is conducted regardless of the entity conducting the Level 2 Assessment.
2. (3)Upon trigger of a Level 2 Assessment, the Level 2 Assessment form must be submitted within 30 days to the state.

Level 2 Assessment Triggers
Level 2 Assessment is triggered if any one of the following occurs:

1. A Public Water System incurs an E. coli MCL violation.
2. A Public Water System has a second Level 1 Assessment within a rolling 12-month period.
3. A Public Water System on state-approved annual monitoring has a Level 1 Assessment trigger in 2 consecutive years.

Seasonal System Provisions
The Total Coliform Rule defines seasonal systems and specifies additional requirements for these types of PWSs:

1. A seasonal system is defined as a non-community water system that is not operated as a PWS on a year round basis and starts up and shuts down at the beginning and end of each operating season.

Start-up Procedures for Seasonal Systems
At the beginning of each operating period, before serving water to the public, seasonal water systems must:

1. Conduct state-approved start-up procedures.
2. Certify completion of state-approved start-up procedures.
3. An exemption from conducting state-approved start-up procedures may be available for seasonal systems that maintain pressure throughout the distribution system during non-operating periods.

Examples of state-approved start-up procedures, which need to be completed prior to serving water to the public, may include one or more of the following:

1. Disinfection.
2. Distribution system flushing.
3. Sampling for total coliform and E. coli.
4. Site visit by state.
5. Verification that any current or historical sanitary defects have been corrected.

Routine Monitoring for Seasonal Systems

1. The baseline monitoring frequency for seasonal systems is monthly.
2. A reduced monitoring frequency may be available for seasonal systems that use ground water only and serve fewer than 1,000 persons.

Other Provisions for the State Drinking Water Agency Special Monitoring Evaluation

The state must perform a special monitoring evaluation at all ground water systems serving 1,000 or fewer persons during each sanitary survey to review the status of the Public Water System and to determine whether the sample sites and monitoring schedule need to be modified.

Major Violations
E. coli MCL Violation
A Public Water System will receive an E. coli MCL violation when there is any combination of an E.coli positive sample result with a routine/repeat Total Coliform positive or E. coli positive sample result:

E. coli MCL Violation Occurs with the Following Sample Result Combination

Routine Repeat

EC+ TC+
EC+ Any missing sample
EC+ EC+
TC+ EC+
TC+ TC+ (but no E. coli analysis)

Treatment Technique Violation
A PWS will receive a Treatment Technique violation when any of the following occur:

1. Failure to conduct a Level 1 or Level 2 Assessment within 30 days of a trigger.
2. Failure to correct all sanitary defects from a Level 1 or Level 2 Assessment within 30 days of a trigger or in accordance with the state-approved timeframe.
3. Failure of a seasonal system to complete state-approved start-up procedures prior to serving water to the public.

Key Points for Public Water Systems to Remember

Find and correct sanitary defects as soon as you become aware of them. This can help reduce E. coli MCL violations, which trigger a Level 2 Assessment. This can help reduce TC+ sample results, which may trigger a Level 1 Assessment.

Make sure to collect all routine and repeat samples as required. Timely and correct monitoring can help reduce triggering a Level 1 or Level 2 Assessment because:

1. Failure to conduct repeat monitoring triggers a Level 1 Assessment.
2. A Level 1 Assessment triggered twice within a certain timeframe triggers a Level 2 Assessment.

GROUND WATER TREATMENT RULE

EPA issued the Ground Water Rule (GWR) to improve drinking water quality and provide protection from disease-causing microorganisms. Water systems that have groundwater sources may be susceptible to fecal contamination. In many cases, fecal contamination can contain disease-causing pathogens.

The purpose of the Ground Water Rule (GWR) is to reduce disease incidence associated with harmful microorganisms in drinking water.

The Ground Water Rule applies to public water systems that use ground water as a source of drinking water. The rule also applies to any system that delivers surface and ground water to consumers where the ground water is added to the distribution system without treatment. The Ground Water Rule was published in the Federal Register in November 2006.

Overview of the Rule

Ground Water Rule (GWR)
71 FR 65574, November 2006, Vol. 71, No. 216
Correction 71 FR 67427, November 2006, Vol. 71, No. 224

Purpose
The rule should reduce the risk of illness caused by microbial contamination in public ground water systems (GWSs).

General Description
The Groundwater Rule establishes a risk-targeted approach to identify groundwater systems susceptible to fecal contamination, and the rule requires corrective action to correct significant deficiencies and source water fecal contamination in all public groundwater systems.

Utilities Covered
The Ground Water Rule applies to all public water systems that use groundwater, including consecutive systems, except that it does not apply to public water systems that combine their groundwater with surface water or with groundwater under the direct influence of surface water prior to treatment.

Public Health Benefits
Targeted protection for over 70 million people served by groundwater sources that are not disinfected or receive less than 4-log treatment or reduction in 99.99% harmful microorganisms. Implementation created an avoidance of 42,000 viral illnesses and 1 related death annually.

Requirements for Drinking Water Systems

New groundwater sources must meet triggered source water monitoring requirements or conduct compliance monitoring. Groundwater systems must conduct triggered source water monitoring if the system does not provide at least 4-log virus inactivation, removal, or a state-approved combination of these technologies before or at the first customer and the system is notified that a sample collected for the Total Coliform Rule (TCR) is total coliform-positive.

Groundwater systems identified as a significant deficiency and systems that have had at least one of the five additional groundwater source samples has tested positive for fecal contamination must comply with the treatment technique requirements.

Analytical Methods for Source Water Monitoring

Fecal Indicator Methodology Method:

1. E. coli Colilert
2. Colisure
3. Membrane Filter Method with MI Agar
4. m-ColiBlue24 Test
5. E*Colite Test
6. EC-MUG
7. NA-MUG
8. 9223 B
9. 9223 B
10. EPA Method 1604
11. 9221 F
12. 9222 G
13. Enterococci Multiple-Tube Technique
14. Membrane Filter Technique
15. Enterolert
16. 9230 B
17. 9230 C
18. EPA Method 1600.
19. Coliphage Two-Step, Enrichment, Presence-Absence Procedure
20. Single Agar Layer Procedure
21. EPA Method 1601
22. EPA Method 1602

Major Provisions of Rule

1. Compliance Monitoring
2. Treatment
3. Technique
4. Compliance
5. Monitoring

In order not to be subject to triggered source water monitoring, a groundwater system can notify the state that it provides at least 4-log treatment of viruses using virus inactivation, removal, or a state-approved combination of 4-log virus inactivation and removal before or at the first customer. The groundwater system must then begin compliance monitoring designed to show the effectiveness of their treatment processes.

Groundwater systems that use chemical disinfection and serve more than 3,300 people must continuously monitor their disinfectant concentration. These systems must maintain the minimum disinfectant residual concentration determined by the state.

Groundwater systems that use chemical disinfection and serve 3,300 people or fewer must take daily grab samples or meet the continuous monitoring requirements described for public groundwater systems serving more than 3,300 people.

Groundwater systems using membrane filtration for 4-log treatment of viruses must monitor the membrane filtration process according to state-specified monitoring requirements.

Groundwater systems may use alternative treatment technologies (e.g., ultraviolet radiation [UV]) approved by the state. Groundwater systems must monitor the alternative treatment according to state specified monitoring requirements, and must operate the alternative treatment according to compliance requirements established by the state.

Source Water Monitoring

Triggered Source Water Monitoring

Groundwater systems that do not conduct compliance monitoring and are notified of a total coliform-positive routine sample collected in compliance with the Total Coliform Rule (40 CFR 141.21) must conduct triggered source water monitoring.

Groundwater systems must collect at least one ground water source sample from each source in use at the time the total coliform-positive sample was collected. The triggered source water sample must be analyzed for the presence of a fecal indicator as specified in the rule.

If the triggered source water sample is fecal indicator-positive, the Groundwater system must either take corrective action, as directed by the state, or if corrective action is not required by the state and the sample is not invalided by the state, the Groundwater system must conduct additional source water sampling.

States may waive the triggered source water monitoring requirement if the state determines and documents, in writing, that the total coliform-positive routine sample is the result of a documented distribution system deficiency.

States may develop criteria for distribution system conditions that cause total coliform positive samples. A Groundwater system can document to the state that it met the state criteria within 30 days of the total coliform-positive sample and be exempt from collecting triggered source water sample(s).

States may invalidate a fecal indicator-positive groundwater source sample under specific conditions. If a fecal indicator-positive source sample is invalidated, the Groundwater system must collect another source water sample within 24 hours of being notified by the state of its invalidation decision.

Additional Source Water Sampling

If the state does not require corrective action in response to a fecal indicator-positive triggered source water sample, the Groundwater system must collect five additional source water samples (from the same source), using the same indicator as used in triggered source water monitoring, within 24 hours of being notified of the fecal indicator-positive sample.

Assessment Source Water Monitoring

States have the opportunity to target higher risk GWSs for additional testing. States independently can determine on a case by case basis whether monitoring is necessary and when corrective action needs to be taken.

Treatment Technique Requirements

Groundwater Systems with Significant Deficiencies or Source Water Fecal Contamination

Groundwater systems must take corrective action if a significant deficiency is identified, or if the initial source samples (if required by the state) or one of the five additional groundwater source samples tests positive for fecal contamination. The Groundwater systems must implement at least one of the following corrective actions:

1. Correct all significant deficiencies
2. Provide an alternate source of water
3. Eliminate the source of contamination
4. Provide treatment that reliably achieves at least 4-log treatment of viruses (using inactivation, removal, or a state-approved combination of 4-log virus inactivation and removal) before or at the first customer for the groundwater source.

New Sources

New Ground Water Sources

New sources which come on line after November 2009 are required either to conduct triggered source water monitoring as required by the Groundwater Rule, or provide at least 4-log inactivation, removal, or a state-approved combination of these technologies and conduct compliance monitoring within 30 days of the source being put in service.

Sanitary Surveys

All Ground Water Systems

States are required to conduct sanitary surveys of all Groundwater systems in order to identify significant deficiencies, including deficiencies which may make a system susceptible to microbial contamination.
Following the initial sanitary survey, states must conduct sanitary surveys every 3 years for most Community Water Systems and every 5 years for Non-community Water Systems that provide at least 4-log treatment of viruses or have outstanding performance records, as determined by the state.

SURFACE WATER TREATMENT RULE

The purpose of the Surface Water Treatment Rules (SWTRs) is to reduce illnesses caused by pathogens in drinking water. The disease-causing pathogens include Legionella, Giardia lamblia, and Cryptosporidium.

The SWTRs requires water systems to filter and disinfect surface water sources. Some water systems are allowed to use disinfection only for surface water sources that meet criteria for water quality and watershed protection. This combination of rules is designed to provide protection from microbial pathogens.

Simultaneously, the rules minimize health risks to the population from disinfection byproducts.

For PWSs that use surface water sources and are not required to filter, existing regulations do not require any treatment for Cryptosporidium. New survey data suggest that typical Cryptosporidium levels in the treated water of unfiltered PWSs are higher than in the treated water of filtered PWSs. Thus, Cryptosporidium treatment by unfiltered PWSs is needed to achieve comparable public health protection.

Further, results from recent treatment studies has allowed EPA to develop standards for the inactivation of Cryptosporidium by ozone, ultraviolet (UV) light, and chlorine dioxide. Based on these developments, the EPA has established requirements for all unfiltered PWSs to treat for Cryptosporidium, with the required degree of treatment depending on the source water contamination level. Additionally, the long-term rule addresses risks in uncovered finished water storage facilities, in which treated water can be subject to significant contamination as a result of runoff, bird and animal wastes, human activity, algal growth, insects, fish, and airborne deposition. Existing regulations prohibit the building of new uncovered finished water storage facilities. Under the long-term rule, PWSs must limit potential risks by covering or treating the discharge of such storage facilities. The requirements in the Surface Water Treatment Rule reflect consensus recommendations from the Stage 2 Microbial and Disinfection Byproducts (M–DBP) Federal Advisory Committee. These recommendations are set forth in the Stage 2 M–DBP Agreement in Principle.

Long-Term Surface Water Treatment Rule

Source Water Monitoring. The rule requires PWSs using surface water or groundwater under the direct influence (GWUDI) of surface water to monitor their source water (the influent water entering the treatment plant) to determine an average Cryptosporidium level. Monitoring results determine the extent of Cryptosporidium treatment requirements.

Large PWSs (serving at least 10,000 people) must monitor for Cryptosporidium (plus E. coli and turbidity in filtered PWSs) for a period of two years. To reduce monitoring costs, small filtered PWSs (serving fewer than 10,000 people) initially monitor just for E. coli for one year as a screening analysis and are required to monitor for Cryptosporidium only if their E. coli levels exceed specified trigger values. Small filtered PWSs that exceed the E. coli trigger, as well as all small unfiltered PWSs, must monitor for Cryptosporidium for one or two years, depending on the sampling frequency.

Under the long-term rule, specific criteria are set for sampling frequency and schedule, sampling location, using previously collected data, providing treatment instead of monitoring, sampling by PWSs that use surface water for only part of the year, and monitoring of new plants and sources. The long-term rule also establishes requirements for reporting of monitoring results, using analytical methods, and using approved laboratories. The rule also requires a second round of monitoring to begin approximately 6.5 years after the first round concludes in order to determine if source water quality has changed to a degree that should affect treatment requirements.

The long-term rule establishes risk-targeted treatment technique requirements to control Cryptosporidium in PWSs using surface water or GWUDI. These treatment requirements supplement those established by existing regulations. Filtered PWSs are classified in one of four treatment categories (or bins) based on the results of the source water Cryptosporidium monitoring. This bin classification determines the degree of additional Cryptosporidium treatment, if any, that filtered PWS must provide. PWSs classified in Bins 2, 3, or 4 must achieve 1.0 to 2.5-log of treatment (90 to 99.7 percent reduction) for Cryptosporidium over and above that provided with conventional treatment. Different additional treatment requirements may apply to PWSs using other than conventional treatment, such as direct filtration, membranes, or cartridge filters.

Filtered PWSs must meet the additional Cryptosporidium treatment required in Bins 2, 3, or 4 by using one or more treatment or control processes from a microbial toolbox of options. The long-term rule requires all unfiltered PWSs to provide at least 2-log (99 percent) inactivation of Cryptosporidium. If the average source water Cryptosporidium level exceeds 0.01 oocysts/L, the unfiltered PWS must provide at least 3-log (99.9 percent) inactivation of Cryptosporidium. Further, under the long-term rule, unfiltered PWSs must achieve their overall inactivation requirements (including Giardia lamblia and virus inactivation) using a minimum of two disinfectants.

PWSs with uncovered finished water storage facilities must take steps to address contamination risks. Existing regulations require PWSs to cover all new storage facilities for finished water but do not address existing uncovered finished water storage facilities. Under the long-term rule, PWSs using uncovered finished water storage facilities must cover the storage facility or treat the storage facility discharge to achieve inactivation and/or removal of 4-log virus, 3-log Giardia lamblia, and 2-log Cryptosporidium on a state-approved schedule.

The rule applies to all PWSs using surface water or GWUDI, including large and small PWSs, community and non-community PWSs, and non-transient and transient PWSs. Wholesale PWSs must comply with the requirements of the rule based on the population of the largest PWS in the combined distribution system.

Consecutive PWSs that purchase treated water from wholesale PWSs that fully comply with the monitoring and treatment requirements of the rule are not required to take additional steps for that water.

Existing Regulations for Microbial Pathogens in Drinking Water

1. The Surface Water Treatment Rule (SWTR) (54 FR 27486, June 1989) applies to all PWSs using surface water or ground water under the direct influence (GWUDI) of surface water as sources (Subpart H PWSs). It established MCLGs of zero for Giardia lamblia, viruses, and Legionella, and includes the following treatment technique requirements to reduce exposure to pathogenic microorganisms:
   a. Filtration, unless specific avoidance criteria are met
   b. Maintenance of a disinfectant residual in the distribution system
   c. Removal and/or inactivation of 3-log (99.9%) of Giardia lamblia and 4-log (99.99%) of viruses
   d. Maximum allowable turbidity in the combined filter effluent (CFE) of 5 nephelometric turbidity units
   e. (NTU) and 95th percentile CFE turbidity of 0.5 NTU or less for plants using conventional treatment or direct filtration
   f. Watershed protection and source water quality requirements for unfiltered PWSs

2. The Total Coliform Rule (TCR) (54 FR 27544, June 1989) applies to all PWSs. It established an MCLG of zero for total and fecal coliform bacteria and an MCL based on the percentage of positive samples collected. Coliforms are used as an indicator of fecal contamination and to determine the integrity of the water treatment process and distribution system. Under the Total Coliform Rule, no more than 5 percent of distribution system samples collected in any month may contain coliform bacteria (no more than 1 sample per month may be coliform positive in those PWSs that collect fewer than 40 samples per month). The number of samples to be collected in a month is based on the number of people served by the PWS.

3. Interim Enhanced Surface Water Treatment Rule (63 FR 69478, December 16, 1998) (USEPA 1998a) applies to PWSs serving at least 10,000 people and using surface water or GWUDI sources. Key provisions established by the interim rule include the following:
   a. An MCLG of zero for Cryptosporidium
   b. Cryptosporidium removal requirements of 2-log (99 percent) for PWSs that filter
   c. More stringent turbidity performance standards of 1.0 NTU as a maximum and 0.3 NTU or less at the 95th percentile monthly for treatment plants using conventional treatment or direct filtration
   d. Requirements for individual filter turbidity monitoring
   e. Disinfection benchmark provisions to assess the level of microbial protection that PWSs provide as they take steps to comply with new disinfection by-products standards
   f. Inclusion of Cryptosporidium in the definition of GWUDI and in the watershed control requirements for unfiltered PWSs
   g. Requirements for covers on new finished water storage facilities
   h. Sanitary surveys for all surface water systems regardless of size

The interim surface water treatment rule was developed in conjunction with the Stage 1 Disinfectants and Disinfection Byproducts Rule (Stage 1 DBPR) (63 FR 69389, December 1998), which reduced allowable levels of certain DBPs, including trihalomethanes, haloacetic acids, chlorite, and bromate.

4. Long Term 1 Enhanced Surface Water Treatment Rule (67 FR 1812, January 2002) builds on the microbial control provisions established by the interim rule for large PWSs through extending similar requirements to small PWSs. The long-term interim rule applies to PWSs that use surface water or GWUDI as sources and that serve fewer than 10,000 people. Like the interim rule, the long-term rule established the following:
   a. 2- log (99 percent) Cryptosporidium removal requirements by PWSs that filter
   b. Individual filter turbidity monitoring and more stringent combined filter effluent turbidity standards for conventional and direct filtration plants
   c. Disinfection profiling and benchmarking; inclusion of Cryptosporidium in the definition of GWUDI and in the watershed control requirements for unfiltered PWSs
   d. The requirement that new finished water storage facilities be covered.

5. Filter Backwash Recycle Rule (66 FR 31085, June 2001) requires PWSs to consider the potential risks associated with recycling contaminants removed during the filtration process. The provisions of the filter backwash rule apply to all PWSs that recycle, regardless of population served. In general, the provisions include the following:
   a. PWSs must return certain recycle streams to a point in the treatment process that is prior to primary coagulant addition unless the State specifies an alternative location
   b. Direct filtration PWSs recycling to the treatment process must provide detailed recycle treatment information to the State
   c. Certain conventional PWSs that practice direct recycling must perform a one-month, one-time recycling self-assessment

Introduction to Cryptosporidium

Concern with Cryptosporidium in Drinking Water

EPA is promulgating the Long-Term Surface Water Treatment Rule to reduce the public health risk associated with Cryptosporidium in drinking water.

Public Water System

The function of a public water system (PWS) is to provide water from a source, treat the water to render it suitable for its intended use, and deliver the water to the user at the time and in the quantity desired. Since such factors as the yield and quality of raw water sources; topography, geology, and population density of service areas; and intended uses of water may vary, it is obvious that not all water systems will be alike. Nevertheless, there are certain general considerations that designers of virtually all water systems must take into account.

A public water system provides water for human consumption through pipes or other constructed conveyances to at least 15 service connections or serves an average of at least 25 people for at least 60 days a year. A public water system may be publicly or privately owned.

Almost everyone drinks water from a public system at some point: while at school, at work, in a restaurant, or on vacation.

Public service use includes public pools, parks, firefighting, water and wastewater treatment, and municipal buildings, and some is unaccounted for because of leaks, flushing, tower maintenance, and other system losses. Domestic deliveries represent the largest single component of public-supply withdrawals.

Domestic water use includes indoor and outdoor uses at residences, and includes uses such as drinking, food preparation, bathing, washing clothes and dishes, flushing toilets, watering lawns and gardens, and maintaining pools. Domestic water use includes potable and non-potable water provided to households by a public water supplier (domestic deliveries) and self-supplied water use. Self-supplied domestic water use is typically withdrawn from a private source, such as a well, or captured as rainwater in a cistern.

In 36 States, including Puerto Rico and the U.S. Virgin Islands, surface-water sources provided more than half of the total public-supply withdrawals.

Three States—California, Florida, and Texas—accounted for 37 percent of total groundwater withdrawals for public supply.

States that relied on groundwater for 75 percent or more of their public-supply withdrawals were Hawaii, Idaho, Florida, Mississippi, Iowa, and Nebraska.

Water Quality

Water quality requirements are directly related to intended use. The highest intended use considered is human consumption. Although, only about 1% of water is used for drinking and cooking, the quality standard for all public water supplies is based on the use of water for those purposes. These standards include physical, chemical, bacteriological, and radiological requirements that are applicable to water sources as well as finished waters. Water that is suitable for human consumption is of high enough quality to serve most commercial and many industrial activities. When higher quality water is required, point-of-use (POU) treatment is generally preferable to providing additional treatment of the entire water supply.

While it is true that many areas of the United States possess some of the best drinking water on earth, at times that water may fall short of meeting our health needs.

The quality of your water depends on many factors:

• Your location
• Your water source
• Your treatment plant’s efficiency
• The condition of the pipes coming to your home

Customers that are served by a public water system can contact their local water supplier and ask for information on contaminants in their drinking water, and are encouraged to request a copy of their Consumer Confidence Report. This report lists the levels of contaminants that have been detected in the water, including those by EPA, and whether the system meets state and EPA drinking water standards.

Water Treatment

Water prior to treatment is called raw water. If a public water supply is to be considered safe, it must be properly treated. The most important water treatment process is disinfection. Water that has been properly treated and is safe for public use is called potable water. Potable water is free of disease-causing organisms, has a chlorine residual and is safe for public consumption. A public water system can only deliver potable water to its customers.

The degree of treatment that a given water will require prior to routine use for human consumption depends primarily upon the initial quality of that water. Since natural water quality may vary widely between sources, and from day to day for a given source, treatment requirements also vary.

Pumping, Storage, and Distribution

Pumping, storage, and distribution facilities are needed to deliver treated water to users in response to widely varying rates of demand. Since all three components must work together to serve this purpose, their designs must be carefully integrated.

Operation and Maintenance

As a general rule, public water systems should be designed to require the minimum level of operation and maintenance that is commensurate with satisfactory delivery (quantity and quality) of water to the users. This requires those who oversee the operation of a public water system (PWS) to give ample consideration to the reliability of processes and equipment, to anticipate the types of failures that are likely to occur, and to make provisions for dealing with them with as little disruption in service as is possible. Failure to anticipate and make adequate provisions for dealing with failures is perhaps the most common shortcoming of the typical water system.

In order, to help the operators of a PWS cope with problems that may arise, it is common practice to provide a system operation manual and for the supplier to furnish an operation and maintenance (O&M) manual for each piece of equipment. In some states, a system operation manual is not optional, but a requirement. These documents should provide instructions for operating the system under various scenarios (e.g., normal, peak demand, and minimum demand periods as well as various types of emergency situations), preventative and routine maintenance procedures, and troubleshooting. If the operation and maintenance (O&M) manual is developed as the system is being designed, rather than after final plans are prepared, as is often the case, many pitfalls can be avoided. In developing the O&M manual, it is important to remember that many public water systems are operated by fairly nontechnical, personnel. Thus, unambiguous, clearly explicit instructions should be given

It is important for a PWS to maintain a minimum of three (3) copies of these manuals. One should be located in a convenient place for the operators, this copy is usually called a “field” copy. Another copy should be available for management reference, this copy is normally called an “office” copy. And one complete copy for the archives. These days, for convenience and to save space, digital copies of these manuals can substitute for print copies and be maintained as management and archives copies.

The information in this site is intended solely for the personal non-commercial use of the user who accepts full responsibility for its use. While we have taken every precaution to ensure that the content of this site is both current and accurate, errors can occur.

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The Toxic Substances Control Act (TSCA) 

Section 8 (b) of the Toxic Substances Control Act (TSCA) requires EPA to compile, keep current and publish a list of each chemical substance that is manufactured or processed, including imports, in the United States for uses under TSCA. Also called the “TSCA Inventory” or simply “the Inventory,” it plays a central role in the regulation of most industrial chemicals in the United States.

The initial reporting period by manufacturers, processors and importers was January to May of 1978 for chemical substances that had been in commerce since January of 1975. The Inventory was initially published in 1979, and a second version, containing about 62,000 chemical substances, was published in 1982. The TSCA Inventory has continued to grow since then, and now lists more than 86,000 chemicals.

As part of EPA’s commitment to strengthen the management of chemicals and increase information on chemicals, the Agency provides free access to the inventory online.

TSCA defines a “chemical substance” as any organic or inorganic substance of a particular molecular identity, including any combination of these substances occurring in whole or in part as a result of a chemical reaction or occurring in nature, and any element or uncombined radical.

Chemicals substances on the Inventory include:

• Organics;
• Inorganics;
• Polymers; and
• Chemical substances of unknown or variable composition, complex reaction products, and biological materials (UVCBs).

Chemical substances not on the Inventory are those with uses not regulated under TSCA. The use of these chemical substances is governed by other U.S. statutes on, for example:

• Pesticides,
• Foods and food additives,
• Drugs,
• Cosmetics,
• Tobacco and tobacco products,
• Nuclear materials, or
• Munitions.