Division of Environmental and Community Health

Maine Center for Disease Control & Prevention

A Division of the Maine Department of Health and Human Services

DHHSMeCDCEnvironmental and Community HealthDrinking WaterPublic Water SystemsCore Concepts

Drinking Water Core Concepts

Page Index

Protect Your Source

Take Required Samples

Maintain Treatment

Inspect Your Pipes and Tanks

More Information

The Drinking Water Program promotes a core message of four concepts that ensure public water systems provide safe drinking water to their customers: source protection, sampling, treatment, and maintenance of tanks and pipes. The core concepts encourage water systems to continually work to identify, reduce, and eliminate risks and vulnerabilities to their water systems.

The four concepts direct public water systems toward the overarching goal of ensuring safe drinking water for all their consumers. The DWP works to convey this message to all of Maine’s public water systems on a daily basis through every interaction – whether it be a phone call, site visit, training session, or a DWP email alert.


Protect Your Source

The ideal drinking water source is in a remote, forested natural area with no nearby sources of pollution. However, most water sources are located near more densely populated areas, increasing the vulnerability of the source to contamination. Contamination, whether from harmful chemicals or biological organisms, often comes from activities on the land close to a drinking water source.

The Safe Drinking Water Act requires all public water systems to produce safe water through a multiple-barrier approach. Source protection is the first and most important component of these barriers. If pollutants never reach a drinking water source, the risk for human consumption is greatly diminished – even if other barriers fail. Additionally, treating a contaminated drinking water source is typically much more costly than protecting a drinking water source area.

Approval of a new public water system well requires contamination sources, particularly leach fields and underground fuel storage tanks, to be set back a minimum distance from the well. The Maine Rules Related to Drinking Water require all public water system wells to be 300 feet from potential sources of contamination and 1,000 feet from underground fuel storage tanks.

When these setback distances cannot be met for unavoidable reasons, such as limited property size or wetlands, the DWP administers setback waiver policies that help to mitigate the increased risk created by reduced setbacks. Mitigation may include increased sampling, well construction requirements, or, in some cases, a pre-treated septic process or the installation of drinking water treatment for the removal of any contaminants from the water supply. The DWP’s public water system inspectors administer these setback waiver policies whenever a well with reduced setback is proposed for approval.

Source Protection Measures

Synthetic Organic Compound Waivers

All community and non-transient non-community public water systems are required to test for synthetic organic chemicals (SOCs) at least once every 9 years. Systems have the option to apply for a waiver from testing for SOCs during the first two 3-year cycles of a 9-year period, but are required to sample for SOCs in the last 3-year cycle. Any public water system seeking a waiver from SOC sampling must provide an approved wellhead or watershed protection plan and be able to demonstrate that land within a specified distance of each source is not under threat from SOC use based on land use type. For most land uses a radius of 1,000 feet is used, although a 2,500-foot radius is used for landfills, Superfund sites, and similar higher risk land uses. Systems with waivers can save up to $1,000 per source for each 3-year monitoring/waiver period.

Filtration Avoidance

The Surface Water Treatment Rule requires all public water systems with sources from surface water or groundwater under the influence of surface water to disinfect and filter the drinking water they provide to their consumers.

Only those systems demonstrating compliance with the most stringent water quality criteria set forth in the Rule may qualify for filtration avoidance. Maine has nine community water systems that qualify for, and currently maintain, filtration avoidance.


Take Required Samples

Sampling is considered the best way of determining the quality of drinking water and ensuring it is free of contaminants such as lead, arsenic, nitrates, and bacteria. In Maine, public water systems are required to regularly test the water they provide to consumers and report the results to the DWP. The Safe Drinking Water Act lists 86 contaminants for which water systems must test. Any test results exceeding the standard (MCL) may require treatment, replacement of source, or blending with other sources to reduce the contamination level. Testing schedules are based on a frequency that is reasonable for the protection of public health.

All public water systems must sample their drinking water periodically to ensure that the water is safe to drink. Sampling on a regular schedule will also indicate whether a water system is performing the way it is designed, and can help draw attention to potentially serious problems with the source, treatment, or distribution system.


Maintain Treatment

Although no two public water systems are exactly the same, they all share the same goal of providing safe, reliable drinking water to the communities they serve. To meet this goal, many water systems must treat their water to remove potentially harmful contaminants. The types of treatment provided by a public water system vary depending on the size of the system, the source (groundwater or surface water), and the quality of the source water. An important part of delivering safe drinking water, treatment is only successful when the proper chemicals are applied in the correct amounts and all equipment and materials are regularly maintained and monitored. Effective oversight of treatment systems helps to ensure that high-quality drinking water is delivered to the public.

All public water systems that add chemicals to their water must submit a monthly operating report (MOR) to the DWP. These reports help track the amount of chemical used, daily production of the water system, and the amount of chemical residual present in the distribution system. The DWP reviews monthly operating reports to ensure that each public water system’s treatment is operating efficiently and effectively, providing clean, safe drinking water.


Inspect Your Pipes and Tanks

A water system’s distribution system, a network of piping and storage tanks, is an integral part of its ability to provide safe, clean water to consumers. It is important for water systems to regularly inspect their distribution systems as contaminants can enter drinking water through damaged pipes or tanks. Routine inspection and maintenance may also help water systems save money if they are able to find and repair leaks in a timely manner to abate water loss.


More Information

View or download the Core Concepts as PDFs:

Source Water Protection

Water Sampling and Testing


Drinking Water State Revolving Fund (DWSRF)

Updated 1/4/2023