The safety and quality of publicly supplied and treated tap water is a subject of constant public interest. Unlike uniform bottled products, tap water composition varies significantly based on the source, infrastructure, and local treatment methods. Determining whether tap water is beneficial or poses a risk requires understanding the systems in place to ensure its safety and the specific compounds present. The answer to whether tap water is good for you is highly dependent on where you live.
How Tap Water is Regulated for Safety
In the United States, the federal government establishes the framework for safe drinking water through the Safe Drinking Water Act (SDWA), passed in 1974. This law grants the Environmental Protection Agency (EPA) the authority to set National Primary Drinking Water Regulations (NPDWRs). These NPDWRs are legally enforceable standards that limit the concentration of over 90 different contaminants, including harmful chemicals and microorganisms, allowed in public water systems.
Local water utilities are responsible for the daily treatment and delivery of water that meets these federal and state standards. The treatment process typically involves coagulation, sedimentation, filtration, and disinfection, often using chlorine, to remove pathogens and particulates. Utilities must follow mandated testing schedules and provide annual water quality reports, known as Consumer Confidence Reports, to customers detailing detected contaminant levels. This system provides a baseline of health protection for nearly all Americans served by public water systems.
Essential Minerals and Trace Nutrients
Beyond providing hydration, tap water can be a source of beneficial compounds that contribute to human health. As water travels through the earth’s geology, it naturally dissolves various trace elements and minerals. These naturally occurring components often include calcium and magnesium, which are prevalent in “hard water.”
Both calcium and magnesium are readily absorbed from water and play roles in bodily functions. Magnesium consumption has been associated with cardiovascular health and regulating blood pressure. Many municipalities also intentionally add fluoride to the water supply, a public health measure proven to strengthen tooth enamel and reduce dental decay.
Common Contaminants and Infrastructure Risks
Despite regulatory efforts, two main categories of risk can compromise water quality before it reaches the tap: source contamination and aging infrastructure. Source contamination occurs when raw water from rivers or groundwater is polluted by human activity or natural processes. For example, agricultural runoff introduces nitrates and pesticides, while industrial activity can introduce synthetic chemicals like Per- and Polyfluoroalkyl Substances (PFAS).
PFAS, often called “forever chemicals,” are resistant to breakdown and have been linked to health issues such as liver damage, thyroid disease, and an increased risk of certain cancers. A 2023 study estimated that at least 45% of the nation’s tap water contains one or more types of PFAS. These contaminants are difficult to remove with standard municipal treatment and persist in the environment and the human body.
Infrastructure risks include the leaching of materials from the pipe network, most notably lead from aging service lines and plumbing fixtures. This occurs when corrosive water causes lead to dissolve into the drinking supply, posing a risk to neurological development, particularly in children. Disinfectants, such as chlorine, can react with organic matter in the water to form Disinfection Byproducts (DBPs), including Trihalomethanes (THMs). Long-term exposure to certain DBPs has been associated with an increased risk of bladder and liver cancer, as well as reproductive and developmental effects.
Home Filtration and Testing Methods
Individuals concerned about specific contaminants can take proactive steps through testing and filtration. The first step is to obtain the local Consumer Confidence Report or conduct independent testing, which is the only reliable way to know if odorless and tasteless contaminants like PFAS are present. Certified laboratories offer specialized testing for potential pollutants.
Home filtration systems reduce specific contaminants at the point of use. Activated carbon filters, found in pitchers and faucet-mounted units, are effective at removing chlorine, significantly improving the water’s taste and odor. Carbon filters also reduce volatile organic compounds (VOCs) and some DBPs, but their effectiveness against complex chemicals like PFAS is variable.
For more comprehensive contaminant removal, a reverse osmosis (RO) system is often utilized. This technology forces water through a semipermeable membrane, effectively screening out a variety of dissolved solids, including heavy metals, nitrates, and nearly all types of PFAS. While RO is effective, it typically results in slower water flow and is more expensive than basic carbon filtration.