Is Your Tap Water Safe?

Step 1, Find Your Water System

Your water system is the public utility or private company responsible for treating and delivering your tap water. Most Americans are served by community water systems (CWS) - utilities that serve residential populations year-round. About 10% of people rely on private wells, which are not regulated by EPA and require self-testing.

To identify your water system:

• Check your monthly water bill, it lists the water system name and often a PWS ID number
• Search PlainWater's water systems directory by county or state
• Use EPA's Safe Drinking Water Information System (SDWIS) search at water.epa.gov
• Contact your city or county public works department if you're a renter

Each public water system has a unique PWS ID number (format: PWSID followed by state prefix and 7 digits). PlainWater uses this ID to pull all available data for your system, violations, contaminant test results, population served, and source water type.

Step 2, Check Your System's Violation History

EPA's Safe Drinking Water Information System (SDWIS) tracks all violations reported by public water systems. PlainWater makes this searchable in its systems directory. There are two important categories to understand:

Health-based violations are the most significant. They occur when a contaminant exceeds its Maximum Contaminant Level (MCL), when a required treatment technique isn't applied, or when lead or copper action levels are exceeded. A single health-based violation is not necessarily cause for alarm, some are brief exceedances that were quickly corrected, but a pattern of ongoing or unresolved violations is a meaningful red flag.

Monitoring and reporting violations are more common and usually less serious. They occur when a system fails to collect required water samples or doesn't report results on time. However, a system that consistently misses its own monitoring requirements may have other operational problems worth scrutinizing.

PlainWater's system pages show total violation counts and whether violations are resolved or ongoing. Browse violation data by county to compare your area against regional and national baselines.

Step 3, Read Your Annual Water Quality Report

Community water systems are required by law to distribute an annual Consumer Confidence Report (CCR), also called the Annual Water Quality Report, to all customers by July 1 each year. This document lists every regulated contaminant detected in your water that year, the legal limit (MCL), the actual detected level, and whether any violations occurred.

Your CCR is the most authoritative single-year snapshot of your water quality. Most utilities post current and historical CCRs on their website. Search for "[your city name] water quality report [year]" or contact your utility directly. Renters whose landlords pay for water may not automatically receive a CCR, ask your landlord for a copy or search the utility's website.

When reading your CCR, focus on: contaminants detected above zero (even below the MCL), contaminants that were above the MCL even briefly during the year, and whether the report discloses any health-based violations. The CCR is required to note any violations and explain what was done about them.

Key Contaminants and What They Mean

The table below covers the contaminants that most commonly generate public concern. Detections below MCLs are common and legal; what matters is the level relative to the limit and the health effects documented at higher exposures.

MCL = Maximum Contaminant Level. ppb = parts per billion. ppt = parts per trillion. mg/L = milligrams per liter. Source: EPA National Primary Drinking Water Regulations.

Compiled by the PlainWater research team.

Step 4, Check for PFAS in Your System

PFAS (per- and polyfluoroalkyl substances) are a newer category of concern in drinking water. Under EPA's UCMR5 program (2023–2025), large public water systems were required to test for 29 PFAS compounds. PlainWater includes these 1.93 million test results, searchable by system, state, county, and contaminant.

PFAS detections do not automatically mean your water violates any standard, until water systems must comply with the 2024 MCLs by 2029 (EPA has proposed extending this to 2031, not yet final as of May 2026), many detected levels are below enforcement thresholds. However, any detection is worth tracking, especially for PFOA and PFOS at levels approaching or exceeding 4 parts per trillion. Look up your state's PFAS data through the states directory or your specific system's system page.

If your water system has detected PFAS above health advisory levels, a reverse osmosis filter certified to NSF/ANSI Standard 58 is the most effective point-of-use treatment option. Do not boil water to remove PFAS, it concentrates rather than removes these chemicals.

Step 5, Decide on Filtration

For most Americans served by compliant community water systems, tap water is safe to drink without additional filtration. However, filtration may make sense if:

• Your system has ongoing health-based violations
• PFAS have been detected in your water system above health advisory levels
• Your building has old plumbing (pre-1986) that may leach lead
• You are pregnant, have infants, or have immunocompromised household members
• You rely on a private well (unregulated, test annually)

Match your filter to your water's specific issues. Activated carbon (NSF/ANSI Standard 53) handles chlorine, some VOCs, and certain PFAS. Reverse osmosis (NSF/ANSI Standard 58) is more comprehensive, removing nitrates, arsenic, fluoride, and PFAS. Both are available as under-sink systems or countertop pitchers. Certification by NSF International or the Water Quality Association ensures the product actually removes what it claims.

Special Populations, When to Be More Cautious

EPA's MCLs are set to protect average healthy adults. Certain groups may face elevated risk from contaminant levels that technically comply with federal standards:

• Infants and formula-fed babies: Formula mixed with tap water concentrates any contaminants present. Nitrate levels safe for adults can cause "blue baby syndrome" in infants under 6 months. Lead exposure during infancy has permanent developmental effects.
• Pregnant women: PFAS, lead, nitrates, and certain disinfection byproducts carry elevated risks during pregnancy. The EPA's 2022 PFAS health advisories specifically called out risks to pregnant women and developing fetuses.
• Immunocompromised individuals: People receiving chemotherapy, HIV-positive individuals, and organ transplant recipients are more vulnerable to microbial contaminants. A boil-water notice that is a minor inconvenience for most people represents a serious risk for this group.
• Older adults: Kidney function declines with age, affecting the body's ability to clear contaminants like arsenic and nitrates.

Frequently Asked Questions