All public water systems in the United States are subject to the regulations of the Safe Drinking Water Act (SDWA) which aims to protect public health by ensuring safe public drinking water supplies. The SDWA was enacted by Congress in 1974 and amended in 1986 and 1996. This act gives the United States Environmental Protection Agency (EPA) the authority to set national health-based drinking water standards, sampling and reporting requirements. The act also gives states the authority to set and enact more stringent standards than those set by the EPA. This section summarizes current, recently enacted, and future regulations that apply to Glasgow’s water system.
National Primary Drinking Water Regulations
Under the Safe Drinking Water Act (SDWA), the EPA established National Drinking Water Regulations to control the level of contaminants in the nation’s drinking water. EPA defines a water contaminant as any physical chemical, biological, or radiological substance or matter in water. The regulations establish enforceable limits reflecting both the level that protects human health and the level that water systems can achieve using the best available technology. Besides prescribing these legal limits, EPA rules set water-testing schedules and methods that water systems must follow.
In most cases, the enforceable limit is a Maximum Contaminant Level (MCL). This is the maximum permissible level of a contaminant in water, which is delivered to any user of a public water system. When there is no reliable method that is economically and technically feasible to measure a contaminant at particularly low concentrations, a Treatment Technique (TT) is set in place of an MCL.
National Primary Drinking Water regulations set MCLs for four categories of contaminants. The four categories are listed below and discussed in this Chapter.
- Inorganic Chemicals
- Organic Chemicals
- Disinfectants and Disinfection Byproducts
- Microbiological Contaminants
National Secondary Drinking Water Standards are non-enforceable guidelines for contaminants that cause cosmetic or aesthetic effects in drinking water. The EPA recommends secondary standards but does not require public water systems to comply with secondary MCLs. A list of the EPA secondary contaminants, recommended MCLs, and health effects can be found in Appendix A.
Inorganic Chemicals
Inorganic chemical contaminants in drinking water result from natural processes and man-made chemicals. Inorganic chemicals (IOCs) affect aesthetics including color, taste, and odor. IOCs can be beneficial or harmful. Under the Standardized Monitoring Framework Rule (56 FR 3526), fifteen inorganic chemicals must be sampled. Three separate rules are also included within the inorganic chemical category, and are discussed below.
Lead and Copper Rule
The Lead and Copper Rule (56 FR 26460-26564) is aimed at minimizing lead and copper in drinking water, primarily by reducing water corrosivity. Lead and copper enter drinking water typically through plumbing materials and are exacerbated by high pH, carbon dioxide and alkalinity in the water. Lead and copper ingestion can have health effects ranging from stomach irritation to liver and brain damage depending on exposure concentration and duration. The rule establishes an action level (AL) of 0.015 mg/L (15 ppb) for lead and 1.3 mg/L (1.3 ppm) for copper, based on the 90th percentile of tap water samples. An AL exceedance is not a violation for the water system. However, exceedance of the AL at more than 10 percent of customer taps sampled will result in increased water quality parameter monitoring, corrosion control treatment, source water monitoring/treatment, public education and lead service line replacement.
Radionuclides Rule
Radionuclides are naturally occurring radioactive contaminants. Generally, the naturally occurring radioactive contaminants are at low levels and not a concern, but prolonged exposure to higher concentrations can result in cancer. The Radionuclide Rule (66 FR 76708), which became effective in 2003 was a revision to the original 1976 rule. Under current regulation, samples must be collected from each entry point to the distribution system and tested for beta/photon emitters, gross alpha particles, combined radium 226/228, and uranium. The rule upholds the established MCLs of 5 pCi/L (picocuries per liter) for combined radium 226/228, 4 millirems per year for beta emitters, and 15 pCi/L for gross alpha particles. The rule also establishes an MCL of 30 µg/L (micrograms per liter) for uranium.
Arsenic Rule
Arsenic occurs naturally in rocks and soil, water, air, and plants and animals. Higher levels of arsenic tend to be found in groundwater sources compared to surface water. Studies have linked long-term exposure to arsenic in drinking water to cancer of the bladder, lungs, skin, kidney, nasal passages, liver, and prostate. Non-cancer effects of ingesting arsenic include cardiovascular, pulmonary, immunological, neurological, and endocrine (e.g., diabetes) effects. Short-term exposure to high doses of arsenic can cause other adverse health effects. The Arsenic Rule (66 FR 6976) became effective in 2006 and sets an MCL of 10 µg/L for arsenic. Arsenic in surface water is commonly removed by media filtration, included in Glasgow’s water treatment process.
Organic Chemicals
Organic chemicals are made up of Synthetic Organic Chemicals (SOCs) and Volatile Organic Chemicals (VOCs). SOCs are man-made compounds found in pesticides, defoliants, fertilizers, and fuel additives and often appear seasonally due to application patterns. VOCs are derived from petroleum products and used in cleaning products, fuels, solvents, polishes, and cosmetics. VOCs evaporate (volatize) when exposed to air and dissolve when exposed to liquid. There are 51 combined VOCs and SOCs that must be monitored annually.
Disinfectants and Disinfection Byproducts
Disinfection of drinking water with disinfectants such as chlorine can cause reactions with naturally-occurring organic materials in the water to form disinfection byproducts (DBPs). The document EPA 816-R-01-014, June 2001, states the following:
Since the discovery of chlorination byproducts in drinking water in 1974, numerous toxicological studies have been conducted that show some DBPs to be carcinogenic and/or cause reproductive or developmental effects in laboratory animals.
A major challenge for communities is how to balance the risks from microbial pathogens by using disinfection compared to the formation of DBPs and subsequent health effects. It is important to provide protection from these microbial pathogens while simultaneously ensuring decreasing health risks to the population from DBPs. The SDWA Amendments in August, 1996, required EPA to develop rules to achieve these goals. Below is a discussion on the existing two rules regarding disinfectants and disinfection byproducts; the Stage 1 and Stage 2 Disinfectants and Disinfection Byproducts Rules.
Stage 1 Disinfectants and Disinfection Byproducts Rule
Disinfectants and Disinfection Byproducts
The Stage 1 Disinfectants and Disinfection Byproducts Rule (Stage 1 DBPR) introduced in 1998 established maximum residual disinfection level (MRDL) limits for chlorine, chloramines, and chlorine dioxide and new MCLs for total trihalomethanes and haloacetic acids. Total trihalomethanes (TTHM) are a group of four compounds (chloroform, bromodichloromethane, dibromochloromethane, and bromoform) that are regulated as a total concentration. Five haloacetic acids (HAA5 – monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid and dibromoacetic acid) are also regulated as a total concentration.
The Stage 1 DBPR (63 FR 69690-69476) applies to all community water systems that add a disinfectant during any part of the treatment process. The MRDL for chlorine, which is used at the Glasgow plant, is 4.0 mg/L. The Stage 1 DBPP Rule established the following MCLs, which apply to Glasgow:
- An MCL of 0.080 mg/L for TTHM.
- An MCL of 0.060 mg/L for HAA5.
Monitoring is required in the distribution system in a location representing the maximum residence time. This allows time for formation of any DPBs that may be distributed to water users. Quarterly monitoring is required using a running annual average (RAA) of the last four quarters to determine compliance using dual samples (one sample analyzed for both TTHM and HAA5). Therefore, any one quarterly sample result of either TTHMs or HAA5s above the MCL does not result in a violation. Water systems can be granted reduced monitoring to an annual basis if the results of the quarterly monitoring show two consecutive years of TTHM and HAA5 concentrations less than or equal to 50% of the MCLs. Compliance for annual monitoring is based on the annual sample result. A water system must return to quarterly monitoring if an annual sample of either TTHM or HAA5 is greater than 75% of the MCLs.
Total Organic Carbon
The Stage 1 DBPR also established a required percent removal of total organic carbon (TOC). TOC is used as a surrogate for natural organic matter (NOM) in water, which can be made up of decayed vegetation, algae, etc. This material is termed a DBP precursor. The idea is that if the TOC (and NOM) in source water is reduced, the formation of byproducts in treated water will also be reduced. TOC removal must be achieved through treatment techniques (TTs) known as enhanced coagulation or enhanced softening. The TT requirement only applies to systems with conventional filtration, which is defined as a treatment system including coagulation, flocculation, sedimentation and filtration. Glasgow’s plant is considered a conventional filtration system. Conventional filtration plants already remove a significant portion of turbidity and particulates. Enhanced coagulation is defined as the addition of sufficient coagulant for improved removal of disinfection byproduct precursors such as TOC. The Stage 1 DBPR makes the case that conventional filtration systems have the ability to enhance the treatment process through chemical addition to reduce TOC in the source water to higher levels, in a more affordable manner compared to a plant with sedimentation alone, or a direct filtration plant (no coagulation, flocculation or sedimentation).
The TOC removal requirement is divided into two steps. Step 1 of the rule requires a specific TOC removal percentage based on the source water alkalinity concentration. Table 2-1 summarizes the required removal of TOC by enhanced coagulation and enhanced softening.
Required Percent Removal of Total Organic Carbon (TOC) Using TTs
| Source Water TOC (mg/L) | Source Water Alkalinity mg/L as CaCO3 | ||
| 0-60 | >60-120 | >120 | |
| >2.0 to 4.0 | 35% | 25% | 15% |
| >4.0 to 8.0 | 45% | 35% | 25% |
| >8.0 | 50% | 40% | 30% |
Monitoring of Glasgow’s source water TOC and alkalinity, and treated water TOC (sampled at the combined filter effluent) is required monthly. The monthly TOC removal percentage achieved by the plant is divided by the required removal percentage from Table 2-1 to calculate a removal ratio. Note that the required TOC removal percentage may change each month based on source water alkalinity and TOC. The removal ratio should be greater than 1.0. Compliance with Step 1 is determined by taking each month’s removal ratio, and calculating a running annual average (RAA) on a quarterly basis.
A water system may be exempt from the Step 1 requirements related to the TOC removal requirements if it meets at least one of the following alternative compliance criteria:
- RAA of source water TOC < 2.0 mg/L.
- RAA of treated water TOC < 2.0 mg/L.
- RAA of source water TOC < 4.0 mg/L, RAA of source water alkalinity > 60 mg/L, treated water TTHM < 40 mg/L, and treated water HAA5 < 30 mg/L.
- RAA of treated water TTHM < 40 mg/L and RAA of treated water HAA5 < 30 mg/L with only chlorine for disinfection.
- RAA of source water specific ultraviolet adsorption (SUVA) ≤ 2.0 L/mg-m.
- RAA of treated water SUVA ≤ 2.0 L/mg-m.
A water system may also use a combination of the TT requirements through the Step 1 TOC removal percentages, and alternative compliance criteria 1, 2, 5, and 6 above for compliance on a month to month basis.
If a water system cannot meet the TT limits in Step 1, Step 2 of the rule specifies a bench scale jar test process that allows a water system to determine an alternative, site specific limit upon application to the MDEQ. Glasgow has operated with a site specific limit for many years; 8% TOC removal per MDEQ on-site jar testing. During the project planning phase, bench scale jar testing for the City of Glasgow has been performed as well as pilot testing to determine a process for adequate TOC removal. Results indicate that very high chemical doses are required to achieve adequate TOC removal according to the Stage 1 DBPR. High chemical doses with very low turbidity result in additional chemical sludge output and higher incurred operational costs. Therefore, the City has worked with MDEQ to select a chemical dosage which, when considered with the WTP’s low raw water TOC and historical compliance with the Stage 1 DBPR, results in adequate and achievable TOC removal. The MDEQ may revert back to the requirements in Table 2-1 above, but would then perform additional jar testing for a site-specific TOC removal requirement.
Stage 2 Disinfectants and Disinfection Byproducts Rule
The Stage 2 DBPR (enacted by EPA in 2006) strengthens regulations to protect public health by focusing on additional TTHM and HAA5 monitoring. Systems must also continue to comply with the Stage 1 DBPR, including MRDLs TOC removal requirements and MCLs for TTHM and HAA5. Under the Stage 2 DBPR (71 FR 388), water systems may have to conduct an Initial Distribution System Evaluation (IDSE). The IDSE is intended to identify the locations with high TTHM and HAA5 concentrations. These locations will then be used by the system as the sampling sites for Stage 2 DBPR compliance monitoring. The RAA of TTHM and HAA5 concentrations at the Stage 2 sampling sites must also be less than the MCL. There are four options available for water systems serving less than 10,000 people to meet the IDSE requirements.
- Very Small System (VSS) Waiver. Systems serving fewer than 500 people that have TTHM and HAA5 data automatically receive the VSS waiver unless they are notified by their state that they must conduct an IDSE. Systems receiving the VSS waiver have no further IDSE requirements.
- 40/30 Certification. Systems can meet the IDSE requirements by certifying that all TTHM and HAA5 monitoring results for compliance with the Stage 1 DBPR are less than or equal to 0.040 mg/L for TTHM and 0.030 mg/L for HAA5 during a prescribed two-year time period. The system also must not have had any Stage 1 DBPR monitoring violations for TTHM and HAA5 during the same period. After submitting the required 40/30 certification, systems will have no further requirements under the IDSE unless told otherwise by EPA or the state.
- System Specific Study (SSS). Systems can meet IDSE requirements using existing monitoring results or a distribution system hydraulic model if their data or model meets certain minimum criteria. Systems conducting an SSS must prepare an SSS plan and IDSE report. Existing monitoring requirements were developed to be equivalent to standard monitoring.
- Standard Monitoring. Any system can choose to conduct standard monitoring, even if they receive a VSS waiver, 40/30 certification, or have enough data to conduct an SSS. Standard monitoring includes one year of distribution system monitoring at multiple locations (in addition to Stage 1 DBPR monitoring). The required sampling frequency and minimum number of sample locations depend on the community’s population served and the source water. Systems conducting standard monitoring must complete an IDSE.
The Stage 2 DBPR requires monitoring for TTHM and HAA5 at selected points in the water distribution system. The points are selected with consideration given to the location and time of year when TTHM and HAA5 are likely to be highest. Usually these are points where water has been in the distribution system the longest during warm weather.
Under the Stage 2 DBPR, compliance with the MCLs for TTHM and HAA5 is calculated for each monitoring location in the distribution system. A locational running annual average (LRAA) is used. This approach differs from Stage 1 DBPR requirements, which determined compliance by calculating the running annual average of samples from all monitoring locations across the system. All systems must comply with 0.080/0.060 mg/L THM/HAA5 LRAA based on new sampling sites identified by the IDSE. Systems can qualify for reduced monitoring similar to the criteria for the Stage 1 DPBR.
Microbial Contaminants
Microbial contaminants include types of bacteria, viruses, protozoa, and other organisms typically found in source water, in particular surface water. Surface water needs to be disinfected to inactivate (or kill) these organisms. However, disinfectant practices can be problematic for water systems. As discussed earlier in this chapter, disinfectants can react with naturally occurring organic material in the water to form DBPs. Also, certain microbial pathogens, such as Cryptosporidium, are highly resistant to traditional disinfection practices, such as chlorine. One of the major challenges for water systems is the balance between inactivating microbial contaminants using disinfection, and the formation of DBPs.
Below is a discussion on the existing rules regarding microbial contaminants that apply to Glasgow. These rules include the following:
- Total Coliform Rule
- Surface Water Treatment Rule
- Interim Enhanced Surface Water Treatment Rule
- Long Term 1 Enhanced Surface Water Treatment Rule
- Long Term 2 Enhanced Surface Water Treatment Rule
- Filter Backwash Recycling Rule
Total Coliform Rule
The EPA issued the Total Coliform Rule (TCR) in 1989 to control fecal coliforms and Escherichia coli (E. coli) by monitoring total coliform bacterial. The rule (54 FR 27544-27568) established an MCL and monitoring requirements. The total coliform group is a large collection of different kinds of bacteria. The presence of coliform bacterial in drinking water indicates that disease-causing organisms (pathogens) could be in the water system. Pathogens can result in diarrhea, cramps, nausea and vomiting. Fecal coliforms and Escherichia are introduced to water sources through human and animal feces.
The TCR sets the maximum contaminant limit goal (MCLG) for total coliform at zero. The rule also sets an enforceable MCL in which systems must not find coliform in more than five percent of the samples they take each month. If a sample tests positive for total coliform, the system must collect a set of repeat samples within 24 hours. If a routine or repeat sample tests positive for total coliform, it must also be analyzed for fecal coliform and E. coli. A positive result to this last test signifies an acute MCL violation, which necessitates rapid public notification because it represents a direct health risk.
The number of routine samples required each month depends on system size. The current population of Glasgow is greater than 3,301 and below 4,100; therefore, four samples per month must be taken from the distribution system.
Revised Total Coliform Rule
Revisions to the Total Coliform Rule were proposed by EPA in 2010 and went into effect in early 2013. The rule intends to strengthen protection of water systems from coliform bacteria from the TCR. Additional monitoring may be required for repeat samples, especially for high risk systems. Additionally, well operated systems can qualify for reduced monitoring upon meeting certain criteria. The revision establishes an MCLG for E. coli of zero and eliminates the MCLG and MCL for Total Coliform. This was done to provide a more specific organism to indicate potential fecal contamination. Total coliforms are still required to be monitored but are used to trigger a system assessment if occurrence is above a certain frequency.
Surface Water Treatment Rule
The Surface Water Treatment Rule (SWTR) was promulgated in 1989 and seeks to prevent waterborne illnesses caused by microbiological contaminants. The SWTR (54 FR 27486) established criteria for filtration and disinfection of public water systems that rely on surface water or groundwater under the influence of surface water for their source water. Monitoring and reporting requirements were also defined.
The basic requirements of the SWTR are to provide treatment to ensure at least 3-log removal and/or inactivation of Giardia lamblia cysts and 4-log removal and/or inactivation of viruses. The following are the turbidity and disinfection requirements for conventional filtration systems:
- Turbidity in combined filter effluent less than 0.5 nephelometric turbidity units (NTU) in at least 95% of samples each month.
- Turbidity in combined filter effluent cannot exceed 5.0 NTU.
- Turbidity in combined filter effluent must be monitored every four hours or continuously at the same location.
- Entry point residual disinfectant concentration cannot be less than 0.2 mg/L for more than 4 hours.
- Residual disinfectant concentration in the distribution system cannot be undetectable in more than 5 percent of the samples each month for any two consecutive months.
- Entry point residual disinfectant concentration must be monitored continuously.
- Distribution system residual disinfectant concentration must be monitored at the same time and place as the TCR monitoring.
- Heterotrophic plate count (HPC) can be monitored instead of disinfection residual and less than 500 colony forming units (cfu)/mL is considered a detectable concentration in the distribution system.
Interim Enhanced Surface Water Treatment Rule
The Interim Enhanced Surface Water Treatment Rule (IESWTR), promulgated in 1998, amends the 1989 SWTR. The rule (63 FR 69477) applies to water systems serving 10,000 or more people. Therefore, the IESWTR is not applicable to the City of Glasgow. The Long Term 1 Enhanced Surface Water Treatment Rule addresses similar issues for public water systems smaller than 10,000 people. LT1ESWTR is discussed in the following section.
Long Term 1 Enhanced Surface Water Treatment Rule
The Long Term 1 Enhanced Surface Water Treatment Rule (LT1ESWTR) is the small system counterpart of the IESWTR, and was promulgated in 2002. The rule (67 FR 1812) strengthens microbial protection regarding filtration and disinfection, including provisions addressing Cryptosporidium. Public water systems must continue to meet the treatment, monitoring, and reporting requirements of the SWTR. The new provisions in LT1ESWTR include:
- Maximum Contaminant Level Goal (MCLG) of zero for Cryptosporidium.
- 2-log Cryptosporidium removal requirements for systems that filter.
- For conventional and direct filtration systems, the turbidity level of representative samples of a system’s combined filter effluent water must be less than or equal to 0.3 NTU in at least 95% of the measurements taken each month. The turbidity level of representative samples of a system’s filtered water must at no time exceed 1 NTU. Note these values are more stringent than the SWTR.
- Monitoring of combined filter effluent turbidity at least every four hours.
- Continuous monitoring of turbidity for each individual filter.
- Develop disinfection profiling and benchmarking provisions consisting of a graphical representation of Giardia lamblia inactivation each week over a 12-month period. For water systems serving between 500 and 9,999 people.
Long Term 2 Enhanced Surface Water Treatment Rule
The Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) was promulgated in 2006 and builds upon the LT1ESWTR. The LT2ESWTR focuses on additional monitoring and removal/inactivation of Cryptosporidium and does not change the requirements for percent removal/inactivation of Giardia lamblia and viruses established by the SWTR and LT1ESWTR. Cryptosporidium is a protozoan parasite that is resistant to disinfection with chlorine and can cause severe gastrointestinal illness, especially in people with sensitivity such as infants, the elderly, and those with autoimmune illnesses. The LT2ESWTR requires additional source water monitoring and potential treatment upgrades.
The source water monitoring and the compliance schedule for small systems serving less than 10,000 people is less rigorous than for large systems. Instead of measuring Cryptosporidium directly, small systems are allowed to monitor for E. coli, required every two weeks over a year long period. For flowing surface waters, if the annual mean (average) exceeds a trigger value of 50 E. coli per 100ml, Cryptosporidium monitoring will be required. This involves monitoring for Cryptosporidium at least twice per month for 12 months, or once per month for 24 months.
Depending on the concentration of Cryptosporidium in the source water, the LT2ESWTR will require varying degrees of additional treatment or no additional treatment. The concentration of Cryptosporidium will place the treatment facility into one of 4 “bins”. Facilities in Bin 1 will not be required to provide additional treatment. Communities that monitored for E.coli and did not exceed the trigger value are placed into Bin 1.
The City of Glasgow, like most other water systems in Montana, was classified in Bin 1, which requires no additional treatment to remove Cryptosporidium. The City performed 12 months of E.coli monitoring and did not exceed the trigger value. For water systems requiring additional treatment, the LT2ESWTR introduced the Microbial Toolbox, which assigns Cryptosporidium removal/inactivation credits for various treatment processes and water source management practices.
Filter Backwash Recycling Rule
The Filter Backwash Rule (66 FR 31086) was promulgated in 2001. The rule requires public water systems to review their filter backwash water recycling practices to ensure that they do not compromise microbial control. Recycled filter backwash water, sludge thickener supernatant, and liquids from dewatering processes must be returned to a location such that all processes of a system’s conventional or direct filtration processes including coagulation, flocculation, sedimentation (conventional filtration only) and filtration, are employed. Glasgow does not currently recycle their filter backwash. Backwash water is settled and the supernatant is pumped to the City wastewater facility. This rule would become applicable if the water plant were to initiate filter backwash recycle. However, the plant does not have this capability.