How to Interpret your Water Test

The EPA sets water quality standards that public drinking water supplies must meet. Private wells are not regulated, but the EPA standards are widely ‘recommended’. There are primary standards, which are related to health, and secondary standards, which pertain to aesthetic qualities of the water, like taste or staining characteristics.

The general quality of your water can be determined by comparing your water’s value to the recommended value in your report. If your water’s value exceeds the recommended concentration, you might consider ways to filter or clean up the water. We do not offer water filtration installation, but we’re happy to recommend someone who does. If you decide to install a water filter, it is important for you to know that no filter will continue to work indefinitely. Every filter has a useful lifetime, and every filter needs to be replaced or regenerated occasionally, depending on the amount and frequency of your water use, and on the particular contaminant and filtering system.


Fluoride occurs naturally in local bedrock wells. It is beneficial at lower concentrations, but it is a health concern at higher concentrations. The current standards are 2.0 mg/L (secondary standard), and 4.0 mg/L (primary standard) .The reported levels are:

0.5 to 1.5 mg/L some benefit exists
2.0 mg/L to 4.0mg/L tooth enamel staining possible
4.0 mg/L and higher skeletal fluorosis possible

Call your doctor or dentist for more information.


Chloride is present in most waters, and is not considered harmful at concentrations up to 250 mg/L. Higher concentrations occur naturally along the seacoast, or may indicate road salt use. Since sodium chloride is a major component of sewage, high chloride may indicate sewage contamination. High chloride is harmful to metal pipes, and may indicate an unhealthy level of salt for people on low salt diets.

Nitrate & Nitrite

Nitrate is considered unhealthy because of its conversion in the body to nitrite. Nitrite causes methemoglobinemia (blue baby syndrome), a serious condition harmful to infants and to women during pregnancy. Nitrite can react under acidic conditions to form nitrosamines, which are known carcinogens. Both nitrate and nitrite are found in sewage and wastes from humans and farm animals. Nitrate is a component of fertilizer, so agricultural run-off may be responsible for elevated nitrate levels in your water.

Total Coliform Bacteria

We test for coliform bacteria to see if surface water is getting (or has gotten) into your well. Coliform bacteria themselves are not necessarily bad for your health, but many other things on the surface might be.Coliform presence in your well water INDICATES that surface water is getting (or has gotten) into the well, and this may indicate that harmful substances from the surface are also present. Coliform bacteria live all over the surface of the earth, but do not naturally live down in the underground water that your well draws from. Rain water trickles through the ground carrying contaminants from the surface with it. Coliform bacteria and most contaminants are filtered out of the water naturally by the dirt and rocks underground. This natural filtration removes the coliform bacteria and produces the cleaner water in the bedrock that you drill into for your well. When a well is drilled, casing should be inserted all the way down into the bedrock, and after your house pipes are all connected, the well should be bleached to disinfect the system. From this point on, as long as there is no surface water getting into your well, you should not have coliform bacteria present in your water.

E. coli Bacteria

E. coli bacteria are a subset of coliform bacteria. They are present in the intestines (and feces) of warm blooded animals (including humans). Their presence in your drinking water indicates fecal contamination, and possibly the presence of disease causing organisms.


Sodium is naturally present in nearly all waters. Water near the seacoast, or water softened with sodium-form water softeners usually have higher concentrations. High sodium may also indicate contamination from human or animal waste disposal, or from landfill leachate.


Water hardness results from the presence of certain metals, usually calcium and magnesium. Water hardness is reported as ‘calcium carbonate’. General values are:

Soft 0-50 mg/L
Slightly Hard 50-100 mg/L
Hard 100-150 mg/L
Very Hard Greater than 150 mg/L

Hard water is not known to be unhealthy, but it is aesthetically unpleasing. A soap scum can appear on tubs and showers, and a filmy substance may develop in your toilet. You may also notice it takes a lot of soap to work up a lather. Although some ‘scale’ formation in pipes is beneficial as a protective coating, too much scaling will cause an undesirable build-up inside your pipes and fixtures (including your water heater). Water softeners are used to remove excess hardness from your water.


pH is a measure of the acidic or basic character of your water. A pH value below 7.0 is acidic and above 7.0 is basic. Acidic water is corrosive to metal pipes and may impart a metallic taste to the water. Slightly basic water usually indicates the presence of naturally occurring carbonates and bicarbonates.


Iron can stain laundry and porcelain a reddish or orange color and may add a bitter or astringent taste to the water. Water softeners are used to remove iron from your water.


Manganese can stain laundry and porcelain a blackish or grayish color and may add an unpleasant taste to the water. There is also a characteristic medicinal (Band-Aid or iodine) odor to manganese. Water softeners are used to remove manganese from your water.

Lead & Copper

The presence of lead and copper in your water generally indicates that you have corrosive water. There is rarely any significant amounts of lead or copper in well water, but corrosive water will dissolve lead from solder, and copper from pipes. Corrosive water is common in New England, and is usually indicated by water test results showing you have soft acidic water. Bluish green stains in sinks or showers indicate copper dissolving from your pipes. Copper can stain clothing, fixtures, and hair, and adds a metallic taste to your water. You cannot taste lead which has leached into your water, even at high concentrations. Lead builds up in your body and can damage the brain, red blood cells, and kidneys. The greatest risk is to young children and to women during pregnancy. Corrosivity in your water can be reduced through the installation of an acid neutralizer system. Flushing your water until it gets cold (usually less than 1 minute) will greatly reduce any lead and copper content, and lessen health effects.


Arsenic deposits occur naturally in New England wells. Arsenic dissolves into well water from these natural deposits. Arsenic can also contaminate your drinking water from past human activity. Orchard spraying, coal ash disposal, and industrial discharge are three such activities. Currently about 90% of industrial arsenic is used in wood preservative, but it is also used in paints, dyes, metals, drugs, and soaps.

Studies have linked long-term exposure to arsenic in drinking water to cancer, and to cardiovascular, pulmonary, immunological, neurological, and endocrine effects. Reverse osmosis and activated alumina are two filtration methods known to effectively remove arsenic. Oxidation-type iron and manganese removal filters may also be effective. Only drinking and cooking water needs to be treated.