Well water vs. city water: who tests it, what it costs, which is safer

The short answer: city water comes from a public water system that must meet federal Safe Drinking Water Act standards, sample on a schedule set in federal rules, and send its customers a yearly water quality report. A private well is outside that law. In EPA's words, the quality and safety of water from private domestic wells "are not regulated by the Federal Government" under the Safe Drinking Water Act, "nor by most state governments," and "Private well owners are responsible for delivering safe drinking water to their households" (EPA, Private drinking water wells, updated November 2, 2026).

So the real difference is responsibility. A utility tests city water because the law makes it; nobody tests a private well except its owner. Which is safer depends on the water: USGS scientists who sampled untreated groundwater from both kinds of wells the same way concluded that "Overall, the quality of water from domestic and public wells in the United States is similar." What differs is treatment, checking, and who pays when something goes wrong.

Below: rules, testing schedules, the utility's report, what national data measure, and costs. Whether your own water is safe is covered in is well water safe to drink.

Well water vs. city water at a glance

Who regulates each

EPA describes the Safe Drinking Water Act (1974, amended 1986 and 1996) as protecting public health "by regulating the nation's public drinking water supply." It adds: "SDWA does not regulate private wells which serve fewer than 25 individuals" (EPA SDWA overview, updated December 29, 2025).

The line between the two is about who the water serves, not where it comes from. A public water system, in EPA's definition, provides piped water for human consumption to at least 15 service connections or regularly serves an average of at least 25 people for at least 60 days a year (EPA, Information about public water systems, updated March 16, 2026). A well that supplies a small subdivision, a school or a campground can be a public water system. EPA counts over 148,000 public water systems, which "provide drinking water to 90 percent of Americans."

"City water" is not always river or lake water, either. USGS wrote that about 105 million people, "more than one-third of the Nation's population," receive their drinking water from about 140,000 public water systems that use groundwater as their source (USGS Circular 1346, 2010). The difference is that a utility's water is tested on a legal schedule and, where needed, treated before it reaches you.

On the private side, EPA says around 15 percent of the U.S. population, over 43 million people, rely on private wells. CDC: "Tap water from private wells is not regulated, treated, or monitored by officials." A state may still regulate how a well is built; see how a private well works.

Who tests city water, who tests a well, and how often

For a utility, testing is a legal schedule. For a well, it is a recommendation.

Sources: 40 CFR 141.857, 141.855, 141.23, 141.2, 141.202; CDC, Guidelines for Testing Well Water (July 1, 2024).

CDC also says to test a well after repairs, flooding or a change in taste, color or smell, and when someone becomes pregnant or a child moves in, and to "Use a state-certified laboratory." A system serving 30,000 people must take at least 30 bacteria samples a month. A household following CDC takes one a year.

Your utility's CCR vs. your own well test

A Consumer Confidence Report, EPA's consumer page says, is "also known as an annual drinking water quality report." Community water systems must provide one to their customers, and "Reports must be sent by your water supplier each year by July 1." It names the water's source (a lake, river or aquifer), gives "A brief summary of the risk of contamination of the local drinking water source," lists detected regulated contaminants, and covers the health effects of certain violations and the corrective actions taken (EPA, CCR information for consumers, updated November 21, 2025). If you didn't get one, EPA says to contact your water supplier or use its online CCR search. Our guide to finding and reading your water quality report decodes a CCR table column by column.

The report is changing. EPA announced final CCR rule revisions on May 15, 2024, starting in 2027 (EPA, CCR rule revisions, updated November 21, 2025). EPA's Q&A says every CCR will open with a summary identifying "any violations or action level exceedances," and systems serving 10,000 or more people will deliver reports twice a year, by July 1 and December 31; "Community water systems serving less than 10,000 people will continue to deliver CCRs once per year" (EPA, CCR Rule Revisions Q&A, November 2024).

A well owner's equivalent is the lab report. The two answer different questions:

The lead row matters for city homes. EPA says lead "can enter drinking water when plumbing materials that contain lead corrode," service lines are typically the biggest source in homes with lead pipes, and lead pipes are more likely in "older cities and homes built before 1986." Its advice: "Contact your water utility to have your water tested" (EPA, Basic information about lead in drinking water, updated June 18, 2026). See our lead explainer, and for a well report, how to read a well water test report.

What national data say about contaminants in each

Three kinds of national data get quoted, and they measure different things.

Untreated groundwater: USGS sampled domestic and public wells the same way

USGS's National Water-Quality Assessment program sampled untreated water from about 2,100 domestic wells in 48 states (1991 to 2004) and from 932 public-supply wells in parts of 41 states (1993 to 2007). Both studies took samples before any treatment and compared them with the same kind of yardstick: EPA MCLs, or USGS health-based screening levels where no MCL exists. That makes them the closest like-for-like comparison.

Sources: USGS Circular 1332 (DeSimone, Hamilton and Gilliom, 2009), summary and Table 2; USGS Circular 1346 (Toccalino and Hopple, 2010), summary and pages 21-27. The headline figures in both count radon against 4,000 pCi/L.

The authors of the public-well study compared the two themselves. "Overall, the quality of water from domestic and public wells in the United States is similar," they wrote: in both, about one in five samples had a contaminant above a benchmark, and natural trace elements and radionuclides were the most frequent cause. Pesticides and volatile organic compounds were above benchmarks more often in public wells, and some organic contaminants, mostly VOCs, were detected two to six times as often there, "likely because of the proximity of public wells to developed areas and the higher pumping rates used for public wells than for domestic wells." Nitrate above the MCL was "more than twice as frequently" found in domestic wells.

Caveats: the domestic wells "may not be representative of all domestic wells throughout the United States," and bacteria are not in the 23 percent. For public wells, the sampled water "represents the quality of the source water and not necessarily the quality of finished water ingested by the people served by these public wells." USGS adds that source water from about one in five sampled public wells "would require treatment or blending" to get below benchmarks, but "Water utilities, however, are not required to treat water for unregulated contaminants," which made up about 40 percent of the concentrations above benchmarks.

Treatment doesn't remove everything. In 94 paired samples, organic contaminant levels "generally were similar in source and finished water," except disinfection by-products, which were higher in finished water. No finished-water sample had an organic contaminant above a benchmark.

Treated city water: EPA's compliance data

For treated city water, the national numbers come from violations states report to EPA. EPA's America's Children and the Environment indicator: "In 2023, about 7% of children were served by community drinking water systems that did not meet all health standards," down from "almost 20%" in 1993 (EPA, ACE Drinking Water Contaminants, updated August 3, 2026).

This is a different kind of number. It counts children served by systems that did not meet all health-based standards in the year, including treatment rules (about 4 percent of children were affected by violations of EPA's surface water treatment rules), not the share of water samples above a level. EPA warns that reporting is incomplete: about 18 percent of children were served by systems with a monitoring or reporting violation in 2023, which "may mean that some health-based violations were not reported," and "the magnitude of underreporting is not known." Private wells "are not represented in the database": with no rules to violate, there is no comparable count.

Tap water PFAS: one study that sampled both

One study measured the same thing in both kinds of homes. USGS researchers sampled tap water at 716 locations (269 private wells, 447 public supplies) from 2016 to 2021 and found that "PFAS profiles and estimated median cumulative concentrations were similar among private wells and public-supply tapwater," and estimated "that at least one PFAS could be detected in about 45% of US drinking-water samples" (Smalling and others, 2023, Environment International). That is a detection estimate, not a share above a limit. Federal PFAS limits for public systems are still moving: EPA's PFAS page (updated May 18, 2026) says a May 2026 proposal "upholds the NPDWR for PFOA and PFOS" at 4.0 ppt, while another would rescind the limits for four other PFAS measures. None applies to a private well; see our PFAS explainer.

Is well water healthier than city water?

Neither is healthier as a category. Whether well water is good for you depends on what a test finds in it; the same goes for city water, except that the city publishes its results.

The case made for well water is minerals and no added chemicals. USGS found hard water in about 60 percent of sampled domestic wells and calls it "not a health risk, but it is a nuisance" (Circular 1332). It also notes that some natural constituents, such as selenium, "are required in small amounts for normal physiologic function, even though higher amounts may cause adverse health effects." The same study found arsenic, uranium and radon from the same rocks; natural is not the same as safe. See our hard water guide.

Two things are often added to city water. Well water, CDC says, is not "regulated, treated, or monitored by officials":

• Disinfectant. In the USGS public-well study, disinfection was the primary treatment at about three-quarters of the sampled systems, and it forms by-products. EPA's 2023 data put about 1.5 percent of children on systems that violated the rules limiting those by-products. An unchlorinated well has no by-products, and no disinfectant either; CDC's yearly list starts with total coliform.
• Fluoride. USGS notes that fluoride "is often added to public drinking-water systems." CDC "does not mandate community water fluoridation"; "State and local governments decide." CDC's page still recommends 0.7 mg/L (reviewed May 15, 2024). In the USGS domestic-well study, "Most (85 percent or more)" of wells had fluoride below the range CDC recommended at the time (0.7 to 1.2 mg/L), and about 1 percent of samples were above EPA's 4 mg/L MCL. Federal fluoride policy is under review in 2026; our fluoride explainer tracks it.

The honest answer to "is well water good for you" is a test result. If every result sits below its health benchmark, the water is sound for everything that was tested. Arsenic at 30 µg/L, three times the MCL public systems must meet, is a problem however good the water tastes (see arsenic).

What each costs

City water arrives with a bill; well water with a list of jobs. Official sources give only a few dollar figures:

We found no official national price for drilling a well or replacing a pump, so we don't quote one; get quotes from licensed contractors. Lab prices for each test, from state and county labs, are in our well water testing cost guide, and some health departments test for free (free well water testing).

Buying or owning a house with well water

A house with well water comes with the jobs a utility does for city customers. Most are official recommendations rather than legal requirements; sealing a well you stop using is the exception in the states we checked:

Buying? A seller's report that covers only bacteria and nitrate is incomplete (row 4 of the decision table below), and the well and septic system each get their own inspection; see the well inspection guide.

Switching from a well to city water, or keeping both

Many homeowners don't get to choose. When a water main comes down your road, whether you must connect, what the hookup costs and whether you may keep the old well are local and state decisions, so ask the utility and the county health department first. Three things to know:

• The old well can't just sit there. CDC says that if you are no longer using your well, "you must retire it by filling and properly sealing it," and that "In many states, well owners must document retired wells." If it might be used again, keep maintaining it. State sealing rules and grants: old water well guide.
• Keeping a well for the garden means keeping it separate. Minnesota's well rule is an example: no connection between a well and another water supply system unless one of a few exceptions applies, chiefly protection by an air gap or a backflow prevention device meeting the plumbing code (Minnesota Rules 4725.3350). Check your own state's rules.
• A new city connection comes with a CCR. Read it, and in an older house ask the utility about lead testing.

Two worked examples

A house on city water, built in 1960. The town's CCR lists no violations last year. That tells you the system met its standards, not what your own service line and plumbing add. EPA says lead pipes are more likely in homes built before 1986 and testing is the only sure way to know, so ask the utility about a lead test. That is row 2 of the table below.

A house on a well, with the seller's report. The report shows total coliform absent and nitrate 3.1 mg/L as N, and nothing else. Nitrate is below the 10 mg/L MCL that public systems must meet (a yardstick here, not a rule). But the report covers two of CDC's four yearly tests and says nothing about arsenic, radon or uranium. CDC says to contact your health department about what else to test for where you live; do that, then order those tests from a state-certified lab before closing. That is row 4. Our well inspection guide covers the rest of a home-sale check.

Decision table: which water, and what to do

Next step

On a well, you are your own water utility, and the first job is the yearly test. Our how often to test well water guide gives CDC's baseline and 26 states' own schedules, and the well water testing guide covers what to order and how to sample. Find a state-certified lab near you in the lab finder, then check your numbers in the results checker.

Questions people ask