Water Quality


The quality of drinking water is an important public health issue because contamination in a single system can expose many people. New Hampshire's (NH) drinking water distribution systems provide high-quality public drinking water to all communities. Occasionally, there are minor contaminations from natural and man-made pollutants. As required by federal and state regulations, all contaminants are monitored and tracked to ensure they are kept at levels that have minimal health impact. State agencies, water suppliers, and water engineers work together to help ensure that drinking water contamination levels are as low as possible. This is done by protecting water sources, treating drinking water to remove contaminants, and monitoring water quality to identify problems as quickly as possible. Ultimately, maintaining the highest quality drinking water depends on protecting our lakes, rivers, and aquifers from contamination.

Water Quality Data Overview

Check out the points below for the main takeaways from this page.

• 54% of NH households get their drinking water from public water systems that are routinely monitored for contamination.

• 46% of NH households get their drinking water from private wells and approximately 3 in 10 contain arsenic, a known carcinogen.

Pennichuck Water Works

Do you ever wonder where your drinking water comes from and how it is regulated? Pennichuck Water Works is engaged in the collection, storage, treatment, distribution, and sale of potable water in the Greater Nashua Public Health Region (GNPHR).

Contaminants in Nashua's Drinking Water

For a full list, click on the button below to view your latest water quality report.

Inorganic Contaminants

Inorganic contaminants often end up in our surface and ground waters. There are many sources of inorganic contamination. While some occur as a result of manmade pollution, others occur because of interactions between nature and pollution. Inorganic contaminants impact the taste, color, and odor of our drinking water, having both beneficial and adverse effects on our health.

Microbiological Contaminants

Microbiological contaminants are a concern to human health at certain levels of exposure. Drinking poorly treated water with these contaminants may cause disease with symptoms including diarrhea, cramps, nausea, and possibly jaundice, along with headaches and fatigue. These symptoms may also be caused by factors other than your drinking water, and medical advice should be sought if symptoms persist. To reduce risk of these adverse health effects, the U.S. Environmental Protection Agency (EPA) and State of NH have set enforceable requirements for treating drinking water. Treatment such as filtering and disinfecting the water will remove or destroy any microbiological contaminants. Water treated to meet U.S. EPA requirements is associated with little to none of these health risks and is considered safe to drink.

Perfluorinated Chemicals

Perfluorinated chemicals (PFCs) are a large group of manufactured compounds used to make products resistant to stains, grease, and water. These chemicals are used in everyday products such as cookware, sofas, carpets, clothes, mattresses, and even in some food packaging. Since they aid in reducing friction, perfluorinated chemicals are also used in automotive, construction, and electronics. To date, there is not enough research to fully understand all sources of human exposure, but people are usually exposed through contaminated water or food, or by using products that contain perfluorinated chemicals.

Minimal studies on the health effects of perfluorinated chemicals on humans have been conducted in the general population. The most commonly studied perfluorinated chemicals are perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). Some associations have been found with reduced female fertility and sperm quality, reduced birth weight, attention deficit hyperactivity disorder (ADHD), increased total and non-HDL (bad) cholesterol levels, and changes in thyroid hormone levels (NCCEH). Perfluorinated chemicals slowly break down in the environment and are very persistent, meaning they bioaccumulate in organisms such as people or wildlife. Perfluorinated chemicals are not stored in body fat, but their half-life, or the amount of time it takes for 50% of the chemical to leave the body, is several years. This elongated elimination time makes it difficult to determine how lifestyle and diet changes influence blood levels (NIH).

Radiological Contaminants

Radiological contaminants, also known as radiologicals, are radioactive particles that occur naturally in areas of uranium and radium deposits or in waste from man-made nuclear reactive processes. They contaminate our drinking water when undesirable radioactive substances enter a water supply. Typically, radiological contaminants occur naturally, but human activity from mining, gas and oil production, fertilizing, building, and recycling can alter and disseminate these chemicals, increasing the potential for human exposure. They can also originate from nuclear power plants and medical facilities, seeping into groundwater or binding to dust in the air that travel into drinking water sources such as rivers, lakes, and streams. Radiological contaminants are dangerous to human health because even in very small concentrations, they pose a risk for developing cancer. All community public water systems are required to test for radiological contaminants.

Secondary Contaminants

Secondary contaminants include chloride, fluoride, iron, manganese, sodium, sulfate, and zinc. When secondary contaminants are present in drinking water, it can cause the water to appear cloudy or colored, or to taste or smell bad. While guidelines, known as standards, in managing secondary contaminants are available, they are not enforced due to the minimal health risks when humans are exposed to the maximum contaminant level. Even though there is no health risk, this could cause the public to stop using water from their public water system even though it is safe to drink due to the way secondary contaminants present. These standards were created to give public water systems guidance on removing these chemicals to levels that are below what most people will find to be noticeable.

Synthetic Organic Contaminants 

Synthetic organic contaminants (SOCs) are man-made, carbon-based compounds used for industrial and agricultural purposes. This group of contaminants includes pesticides, PCBs, and dioxin. Drinking water that exceeds the maximum contaminant level is not safe for human health as it can cause damage to the nervous system, kidneys, and increase risk of cancer. All community public water systems are required to test for synthetic organic contaminants.

Volatile Organic Compounds

Volatile organic compounds (VOCs) are chemicals that are present in the air we breathe and the water we drink. They're used in industry, transportation, agriculture, and household products. These compounds are persistent environmental contaminants that are difficult to remove and can bioaccumulate over time. Exposure to volatile organic compounds in drinking water can cause a variety of adverse health effects depending on the type and duration of exposure. Chronic, low-level exposures may lead to liver damage, cancer, and immune system impairment. Acute, high-level exposures may trigger asthma attacks in individuals living with asthma.

The U.S. Environmental Protection Agency (EPA) estimates that volatile organic compounds are present in 20% of the nation's water supply. Some of the more commonly found volatile organic compounds in drinking water include benzene (enters the water supply though gas or oil spills), methylene chloride (an industrial solvent), trichloroethane (used in septic systems), and tetrachloroethane (used in dry cleaning processes).

Commonly found VOCs in drinking water at Pennichuck water treatment plant in 2019

EPA's maximum contaminant level

Health Equity & Water Quality

A person's health can be seriously impacted by their race, ethnicity, gender, income level, education, and other socioeconomic factors. In regards to water quality...

• Race bears the strongest relationship to slow and ineffective enforcement of the federal drinking water law in communities across the nation (NRDC).

• There is unequal access to safe drinking water, based most strongly on race (NRDC).

• Drinking water systems that constantly violated the law for years were 40% more likely to occur in places with higher percentages of residents who were people of color. Even when actions were taken to compel systems to fix their violations, it took longer for water systems in communities of color to come back into compliance (NRDC).

• Race, together with ethnicity and language spoken, had the strongest relationship to serious longstanding violations and ineffective enforcement of the nation’s drinking water law, the Safe Drinking Water Act. Nearly 130 million people in the U.S. live with drinking water violations, often putting their health at risk. Societal inequality and disinvestment exacerbates this in communities of color (NRDC).

• New Hampshire is a geographic hotspot for plumbing poverty. “Plumbing poverty” as a way to understand water insecurity in the U.S. After adjusting for income, housing type, and other factors, householders who are American Indians are 3.7 times more likely to lack complete plumbing compared with householders who don’t identify as American Indian. Black and Hispanic households are also more likely to be plumbing poor than white, non-Hispanic households, they find (Harvard Kennedy School Shorenstein Center).

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