Water Treatment Facility

Water Quality

Meeting customer expectations for high quality water is our first priority. We know that your water is safe because we regularly monitor and test it for over 90 substances, and it meets or surpasses all federal Safe Drinking Water Act standards. Our modern laboratory is state-certified to conduct over 40 different analyses. And annually, water quality experts collect nearly 6,000 samples and perform 16,000 analyses throughout the system, from Sebago Lake to the tap.

In addition, temperature, pH, turbidity, chlorine residual, ammonia/monochloramine and ozone residual concentrations are monitored via on- line meters located at the plant.

 Potability Certification

Water Quality Analysis

2017 Water Quality Report (2016 data)

Complete Water Quality Analysis

Ask The Water Quality Expert

Common Water Quality Questions


If you don't find answers to your water quality questions here, contact our laboratory by e-mail or phone, 774-5961, ext. 3314.

Common Tests


Total Coliform

Total coliform bacteria samples are collected and analyzed five days a week to ensure proper disinfection throughout the water system. By Rule, 120 samples are required to be tested each month (based on population served) however this number is routinely exceeded. Our monitoring program goes beyond what is required by federal law, and our water systems have always been compliant with drinking water rules. The detection of total coliform bacteria in the water system is very rare.

Coliform bacteria tests are indicator tests. The presence of coliform bacteria in and of itself is not harmful, but it may indicate the presence of E. coli or pathogens that pose health risks.



pH is continually monitored at the treatment facility and in the distribution system along with each total coliform sample collected. The measurement of pH is one of the most important tests in water chemistry. It expresses the degree of acidity and is measured on a scale from 0 (very acidic) to 14 (very basic), with 7 being neutral.

An important part of the water treatment process, corrosion control, is pH dependent. Water with a pH of 8 is less corrosive to water pipes, both in our distribution system and in your home, than that same water at a pH of 6 or 7. For this reason the pH of Sebago Lake water, normally near 6.7, is increased to 8.0 with sodium hydroxide. The pH is routinely monitored throughout the distribution system to ensure the continuation of effective corrosion treatment.

Chlorine Residual

Chlorine residual is continually monitored at the treatment facility and in the distribution system along with each total coliform sample collected. The addition of chlorine to drinking water is primarily to destroy disease-causing organisms through the control of total coliform bacteria. Chlorine is added at the treatment facility and at select areas in the water system to provide continued disinfection as the water travels to your home. The maximum allowable level of chlorine is drinking water is 4.0 mg/L and PWD levels are about half this amount.


Disinfection By-Products

Disinfection by-products or DBP’s can be formed when chlorine interacts with natural organic material in the water such as that left behind from decaying leaves along the lake shoreline. They can also be formed when ozone interacts with certain compounds in Sebago Lake water.  Some chlorine and ozone related DBP’s are  possible carcinogens and must be not be present in large amounts. Routine sample collection has shown that DBP levels are always well below any level of concern.