2016 Annual Water Quality Report


Portland Water District

Published May 2016

1/ 1/15 – 12/31/15

PWSID: ME 0091300 and ME 0091302





  • The Source: Where does your water come from?

  • Ensuring Water Quality: Water Purification and Disinfection

  • Water Quality Analysis

  • About the Regulations

  • Water Safety and Advice:Ask the water guru

  • Health Advisories

  • Steep Falls Supplemental Information

  • More Information

Water, what’s it worth?  It’s a question we’ve been prompting customers to think about over a three year Value of Water outreach campaign.  Stop and think about a day without water – no coffee, no shower, no fire protection.  Take it further and you realize water is a component of nearly every product you touch throughout the day.  It’s essential.  And it’s our job at the Portland Water District to keep it flowing to our customers, uninterrupted.  Residents rely on it, our medical facilities require it, our businesses depend on it.  With 1,000 miles of pipe underground, the water system is virtually invisible – until there is a problem.  When water main breaks occur, our crews quickly respond to restore service to our customers.  It is so important, our investments in water main replacement have continued to increase and $7 million will be spent this year to replace mains.

In this water quality report, you will find a wealth of information on the system that brings you excellent quality water that you can depend on.  

Your drinking water comes from Sebago Lake, Maine’s deepest and second largest lake.  By almost any measure, the quality of water in Sebago Lake is among the highest of any lake in Maine.   It is so clean, in fact, it is exempt from filtration requirements.

The lake is so clean for three main reasons:
1.  It is naturally deep and cold and the soil around the lake doesn’t easily erode;

2.  People have cared for it so well for more than a century and continue to do so; and

3.  The land around the lake – known as the watershed – is mostly covered with forest.   Forested land naturally cleans the water as it makes its way to the lake.

Keeping the lake clean into the future is the best way to ensure you have clean, safe drinking water for decades to come. 

Moderate Risk of Contamination

Although Sebago Lake is very clean today, human activities on and around the lake can pose a risk to water quality. 

The Maine Drinking Water Program has evaluated all public water supplies as part of their Source Water Assessment Program (SWAP).  The assessments reviewed geology, hydrology, land uses, water testing information, and the extent of land ownership or protection by local ordinance to see how likely  drinking water sources are to being contaminated by human activities in the future. Their report on Sebago Lake concludes that the lake is at moderate risk of contamination.

The most significant risks to the long-term protection of Sebago Lake, according to state officials, are boating and ice fishing in Lower Bay and shoreland development.  For more information about the SWAP, please contact the DWP at 287-2070.

Lowering Risk of Contamination

Because the lake is used by so many for various reasons, our efforts to decrease the risk of contamination involve multiple approaches.  Our protection program involves: water quality monitoring, security, inspections, direct actions, education, land acquisition, and land preservation. 

Keeping the land surrounding the lake forested is key to protecting the water quality of the lake since forests naturally clean water.  To help make this happen the Board of Trustees approved an initiative in 2013 to help local land trusts and willing landowners conserve forested land.  The District will contribute up to 25% of the cost of these transactions since our customers directly benefit with cleaner water.  When a willing landowner and land trust apply for financial support, we evaluate the property to determine its value to the overall protection of the lake and choose a level of support accordingly.  Since 2013, the District has contributed to the conservation of nearly 2,400 acres of land in the watershed. 

Conserving forested land helps keep the water in Sebago Lake clean, which means that it does not need as much treatment before it is delivered to customers.  If water quality were to decline significantly, the District would have to add additional treatment to meet drinking water standards.  The cost of this would be much greater than the cost of maintaining forested land through conservation. 

Since 2006, the Portland Water District has contributed $450,000 towards the conservation of nearly 4,000 acres of land in the Sebago Lake watershed. 

Meeting your expectations for high quality water is our first priority. We know your water is safe because we regularly monitor and test it. Our water quality experts performed over 15,000 analyses last year. Many inorganic, synthetic organic and volatile organic chemicals, and disinfection by-products are routinely monitored for and not detected.

Primary disinfection: ozone and ultraviolet light

Secondary disinfection: chloramine

Filtration: None, PWD holds a waiver from filtration due to the purity of Sebago Lake.

pH adjustment: sodium hydroxide

Corrosion control: zinc orthophosphate

Dental health additive: fluoride (hydrofluorosilicic acid)

In 2015, your water met or surpassed every state and federal requirement. Water samples are tested by state-certified testing laboratories including two Portland Water District laboratories which are certified by the Maine Department of Health and Human Services.

Water Quality Analysis

Unregulated Substances are those that do not yet have a drinking water standard set by the USEPA. The purpose of monitoring for these contaminants is to help EPA decide whether or not they should have a standard.

As part of this 2013 monitoring, the Portland Water District tested for several additional unregulated contaminants; all without detection.  This included hormones such as testosterone and estradiol that are produced in the human body and used in pharmaceuticals.                                                            

Definitions and Notes

MCL: Maximum Contaminant Level. The highest level of a contaminant that is allowed in drinking water.

MCLG: Maximum Contaminant Level Goal. The level of a contaminant in drinking water below which there is no known or expected risk to health.

MRDL: Maximum Residual Disinfectant Level. The highest level of a disinfectant allowed in drinking water.

MRDLG: Maximum Residual Disinfection Level Goal. The level of a drinking water disinfectant below which there is no known or expected risk to health. MRDLGs do not reflect the benefits of the use of disinfectants to control microbial contaminants.

LRAA: Locational Running Annual Average. A 12 month rolling average of all monthly or quarterly samples at specific sampling locations. Calculation of the LRAA may contain data from the previous year.  

Variances and Exemptions: State permission not to meet MCL or a treatment technique under certain conditions.

AL = Action Level: The concentration of a contaminant that, if exceeded, triggers treatment or other requirements that a water system must follow. Action Levels for Lead and Copper are measured at the tap of “high risk” homes.  Ninety percent of tests must be equal to or below the Action Level.

ppb: one part per billion.

ppm: one part per million.

mg/L: milligrams per liter, or parts per million.

µg/L: micrograms per liter, or parts per billion

Turbidity: The measurement of cloudiness or suspended colloidal matter (silt). As you can see from the table, all of the samples taken of our water system were well below 5 NTUs.

NTU=Nephelometric Turbidity Units



Fluoride: Fluoride levels must be maintained between 0.5 to 1.2 ppm. The optimum level is 0.7 ppm.

Lead/Copper: Action levels (AL) are measured at consumer’s tap. 90% of the tests must be equal to or below the action level. If present, elevated levels of lead can cause serious health problems, especially for pregnant women and young children. Lead in drinking water is primarily from materials and components associated with service lines and home plumbing. Portland Water District is responsible for providing high quality drinking water, but cannot control the variety of materials used in plumbing components. When your water has been sitting for several hours, you can minimize the potential for lead exposure by flushing your tap for 30 seconds to 2 minutes before using water for drinking or cooking. If you are concerned about lead in your water, you may wish to have your water tested. Information on lead in drinking water, testing methods, and steps you can take to minimize exposure is available from the Safe Drinking Water Hotline or at: http://www.epa.gov/safewater/lead
TTHM/HAA5: Total Trihalomethanes and Haloacetic Acids (TTHM and HAA5) are formed as a by-product of drinking water chlorination. This chemical reaction occurs when chlorine combines with naturally occurring organic matter in water. Compliance is based on locational running annual average.
Nitrate: Nitrate in drinking water at levels above 10 ppm is a health risk for infants of less than six months of age. High nitrate levels in drinking water can cause blue baby syndrome. Nitrate levels may rise quickly for short periods of time because of rainfall or agricultural activity. If you are caring for an infant you should ask advice from your health provider.

About the Regulations

The federal Safe Drinking Water Act directs the state, along with the EPA, to establish and enforce drinking water standards. The standards set limits on certain biological, radioactive, organic and inorganic substances sometimes found in drinking water. Two types of standards have been established. Primary drinking water standards set achievable levels of drinking water quality to protect your health. Secondary drinking water standards provide guidelines regarding the taste, odor, color, and other aesthetic aspects of your drinking water, which do not present a health risk.


Q: I’ve heard a lot about Flint, MI and the high levels of lead in their water.  Should I be concerned about my water here in the Greater Portland area?

A:  The Portland Water District’s tap water meets the Lead and Copper Rule requirements and your water is safe to drink.

When public drinking water systems first began testing for lead in the early 1990s as a result of the then recently released EPA Lead and Copper Rule, many (including  PWD) found lead levels higher than the allowable amounts. Although Sebago Lake does not have lead in it, the Lead and Copper Rule requires water samples be taken from high-risk homes.

PWD immediately conducted a corrosion control study that identified the necessary steps to make the water less corrosive to household plumbing and ultimately reduce lead at the tap.   The Corrosion Control Strategy was successfully implemented under the guidance of the Maine Drinking Water Program.

A survey of the distribution system found no public service lines therefore the primary  strategy involved raising the pH of the water leaving the Sebago Lake facility and adding a corrosion inhibitor, zinc orthophosphate, to minimize lead being leached into the water from home plumbing systems.  At the same time, more than 200 samples per year were collected by customers from their homes and analyzed for lead. 

In 2002 after continued adherence to the strategy, testing showed lead levels consistently below the allowable amount and the Maine Drinking Water Program deemed the program “optimized,” meaning the levels were as low as was practically possible and going forward the chemistry of the water had to be maintained. The Corrosion Control Strategy continues, and we confirm its effectiveness through quarterly water quality tests.  Because of the effectiveness of our program, sampling requirements have been reduced.  Since 2002, all samples continue to show that the Corrosion Control Strategy is successful.

Q: This winter and spring I have noticed a stronger chlorine taste to my water.  Is Portland Water District adding more chlorine?

A: During the winter and spring months PWD actually adds less chloramine (chlorine compound) to the water, but because of the colder water temperature chlorine lasts longer (doesn’t dissipate as quickly) as the water travels through the water distribution system. Therefore, depending where you live, you may experience slightly more chlorine taste in the winter/spring than in the summer/fall.

In the drinking water distribution system, adding chlorine and maintaining a residual amount throughout the water distribution system provides protection against the risk of microbial contamination after treatment. 

More FAQs

Health Advisories

Drinking water, including bottled water, may reasonably be expected to contain impurities or contaminants. However, these contaminants do not necessarily indicate that water poses a health risk and may include:

Microbial contaminants, such as viruses and bacteria, which may come from sewage treatment plants, septic systems, agricultural livestock operations, and wildlife.

Inorganic contaminants, such as salts and metals, which can be naturally occurring or result from urban stormwater runoff, industrial or domestic wastewater discharges, oil and gas production, mining, or farming.

Pesticides and herbicides, which may come from a variety of sources such as agriculture, urban stormwater runoff, and residential uses.

Organic chemical contaminants, including synthetic and volatile organic chemicals, which are by-products of industrial processes and petroleum production and can also come from gas stations, urban runoff, and septic systems.

Radioactive Contaminants, which can be naturally-occurring or be the result of oil and gas production and mining activities.

Some people may be more vulnerable to contaminants in drinking water than the general population. Immunocompromised people such as individuals with cancer undergoing chemotherapy, people who have undergone organ transplants, people with HIV/AIDS or other immune system disorders, some elderly, and infants can be particularly at risk from infections. These people should seek advice about drinking water from their health care providers. Guidelines, jointly developed by the EPA and the CDC, on the appropriate means to lessen the risk of infection by Cryptosporidium, are available from the Safe Drinking Water Hotline (1-800-426-4791) or web site.

More Information

The Portland Water District Board of Trustees generally meet every second and fourth Monday of the month.  The public is welcome to attend meetings.

207.761.8310 (Monday through Friday between 8:00 a.m. and 4:30 p.m.)

Portland Water District

225 Douglass Street

PO Box 3553

Portland, Maine 04102









Environmental Protection Agency            

800.426.4791 |  www.epa.gov/safewater/     


American Water Works Association        

303.794.7711  |   www.awwa.org


National Centers for Disease Control 

404.639.3311 | www.cdc.gov


Maine Drinking Water Program

207.287.2070  |  www.maine.gov

Steep Falls, Standish Supplemental Information

Because the Steep Falls water system is separate from the Greater Portland water system, some components of the Water Quality Report do not apply to your system.  Those sections have been modified and provided below. 

Your Source of Water and Ensuring Water Quality

The Steep Falls well system (Standish) supplies approximately 300 people.  Treatment includes the addition of liquid sodium hypochlorite for disinfection, sodium hydroxide for pH adjustment and corrosion control, aeration for radon removal, and fluoride (sodium fluoride).

The state Drinking Water Program waived the requirement to sample for pesticide, herbicide, carbamate and PCB in the Steep Falls water system through 2016. The waiver was granted based on past water test results and the land uses in the proximity of the wells.  Other testing for inorganic and volatile organic compounds continues at the required frequency.

Additional Definitions
pCi/L: picocuries per liter (a measure of radioactivity)



Gross Alpha: Action level over 5 pCi/L requires testing for Radium 226 and 228. Action level over 15 pCi/L requires testing for Uranium. Compliance is based on Gross Alpha results minus Uranium results = Net Gross Alpha.

Radon: The State of Maine adopted a Maximum Exposure Guideline (MEG) for Radon in drinking water at 4000 pCi/L, effective 1/1/07. If Radon exceeds the MEG in water, treatment is recommended. It is also advisable to test indoor air for Radon. Radon at a level of 1643 pCi/L was detected in Steep Falls’ well water after aeration treatment. Radon is found in the soil and bedrock formations and is a water soluble, gaseous by-product of uranium.  Most radon is released to the air moments after turning on the tap.  Only about 1-2 percent of radon in the air comes from drinking water. Inhalation of radon increases the risk of lung cancer over the course of your lifetime.  If you’d like more information about radon, please contact us or the State Drinking Water Program and request a radon fact sheet.