Which States Have the Best and Worst Tap Water?

If you want to know which states have the best and worst tap water, we’ve compiled a list of all those areas, as well as information on how water quality is determined for each state and the causes of poor quality tap water.

How Water Quality is Determined for Each State

In 1974, Congress passed the Safe Water Drinking Act (SWDA) to protect public health by regulating the nation’s water supply. The Environmental Protection Agency (EPA) establishes standards and regulations for drinking water quality and monitors states, local authorities, and water suppliers implementing those standards. According to the EPA, over 92% of the population receives drinking water supplied by community water systems that meet all health-based standards.

The EPA must take steps to ensure there’s safe drinking water for the public. First, the EPA identifies contaminants that may affect public health. Then, per the SWDA, the EPA sets treatment requirements and maximum contaminant levels — which regulates the level of a determined contaminant in water — for over 90 contaminants commonly found in public drinking water. Additionally, the EPA must conduct routine assessments to determine vulnerabilities and set national standards for tap water and risk reduction.

Within each state, local water suppliers must perform annual tests adhering to the SDWA’s standards and regulations. Once the tests are complete, all local water suppliers must make the water quality report — also known as a Consumer Confidence Report (CCR) — available to all residents.

What Causes Poor Tap Water Quality?

Numerous factors can cause poor quality tap water, including:

Old pipes — One of the main reasons for poor quality tap water is the pipes carrying and distributing the water. The lead or copper from old, corroding pipes can seep into the water, resulting in contamination.
Treatment byproducts — Before water is distributed to the public, it gets taken to a water treatment plant to ensure it’s safe for drinking. While these treatment plants can remove several contaminants, they can leave behind potentially harmful byproducts such as trihalomethanes.
Industry and agriculture — Industrial disposal sites and storage facilities can release organic solvents, heavy metals, and petroleum products, which can migrate into water sources. Additionally, agricultural runoff containing pesticides and fertilizer can contaminate water sources.
Human and animal wastes — Sewage, septic systems, and wastes from animal feedlots can all carry harmful microbes that could potentially end up in water sources.
Natural sources — Some areas of the country have underground conditions with higher levels of certain contaminants than others, such as iron, sulfur, and arsenic. As groundwater travels through rock and soil, it can pick up and absorb these contaminants.

States with the Best Tap Water

Which states have the cleanest tap water? According to data from the EPA and local CCR reports, these states provide the best tap water in the U.S.

Hawaii — In 2021, only one out of Hawaii’s 137 public water systems received a violation from the EPA.
Nebraska — 99% of the state’s 1,300+ public water systems were compliant with the EPA’s standards in 2021.
Minnesota — About 98% of the state’s 6,700+ public water systems were compliant with the EPA’s standards in 2021.
Maryland — In 2021, nearly 97% of the state’s 3,300+ public water systems were compliant with the EPA’s standards.
Alabama — Roughly 96% of the state’s nearly 600 public water systems were compliant with the EPA’s standards in 2021.
Rhode Island — In 2021, 95% of Rhode Island’s nearly 500 public water systems were compliant with the EPA’s standards.
New Hampshire — 94% of New Hampshire’s 2,500+ public water systems were compliant with the EPA’s standards in 2021.
South Carolina — In 2021, 94% of North Carolina’s nearly 1,500 public water systems were compliant with the EPA’s standards.
New York — About 94% of New York’s 8,600+ public water systems were compliant with the EPA’s standards in 2021.
California — In 2021, 94% of California’s 7,500+ public water systems were compliant with the EPA’s standards.

States with the Worst Tap Water

Here are the states with the worst tap water:

West Virginia — Approximately 34% of West Virginia’s 850+ public water systems were compliant with the EPA’s standards in 2021.
Louisiana — In 2021, nearly 62% of the state’s 1,300+ public water systems were compliant with the EPA’s standards.
Connecticut — Almost 67% of the state’s nearly 2,500 public water systems were compliant with the EPA’s standards in 2021.
New Mexico — In 2021, 67% of New Mexico’s nearly 1,100 public water systems were compliant with the EPA’s standards.
Maine — Roughly 69% of the state’s 1,900+ public water systems were compliant with the EPA’s standards in 2021.
Idaho — In 2021, nearly 70% of the state’s 2,000+ public water systems were compliant with the EPA’s standards.
Texas — Approximately 71% of the state’s 7,200+ public water systems were compliant with the EPA’s standards in 2021.
Ohio — 71% of the state’s nearly 4,500 public water systems were compliant with the EPA’s standards in 2021.
Kansas — In 2021, almost 72% of the state’s nearly 1,000 public water systems were compliant with the EPA’s standards.
Oklahoma — In 2021, about 73% of the state’s nearly 1,400 public water systems were compliant with the EPA’s standards.

The Bottom Line

Whether you live in a state with good or bad tap water, you can always improve your home’s water quality with a whole house water filtration system. This type of system connects to your home’s main supply line, so every tap in your house receives refreshing filtered water. It’s a one-stop solution for getting the peace of mind you and your family deserve.

Which States Have the Best and Worst Tap Water?