I have been covering water quality for a decade now. I have tested dozens of water filters — pitcher-type, under-sink, and faucet-mount. I have met with the engineers who designed them, interviewed the people who create and enforce the NSF/ANSI standards for filter certification, and spoken with test-kit manufacturers and certified test labs. I have attended hours of seminars run by experts in water treatment and groundwater remediation. Last year I spent a day at a municipal treatment plant, talking with the executives and engineers in charge of implementing water filtration on an industrial scale.

And I have come to three main conclusions.

1. You don’t have to wonder what’s in your water. “We live in north central Florida, where the water is pretty iffy. I know we need a filtration system of some kind,” wrote Wirecutter reader Marian.

It’s absolutely true that the groundwater in north central Florida has problems.

But “in the groundwater” and “coming out of the faucet” are not the same thing. Water utilities are required by the Safe Drinking Water Act to bring nearly 100 contaminants — from disease-causing bacteria to pesticides to PFOA and PFOS, the most common forever chemicals — below federal thresholds.

Before the treated water goes to anybody’s home, it is tested to confirm that it meets all the requirements, and water utilities are legally required to make the results public in an annual document called a Consumer Confidence Report. If you’re on a public water supply, you can simply look up your CCR; you’ll know what was found in the water, how much of it, and whether any findings exceeded federal and state standards.

If you want even more understanding, you can go further and test the tap water that comes out of your faucet. Doing so is not cheap — but it is much more affordable and far less of a hassle than a lifetime of maintaining a filtration system that you may not have needed in the first place. (Because about 15% of the US populace, or 43 million people, uses water from unregulated private wells, we include both utility and well-water test kits in our guide.)

2. You may not need a water filter. Bad news makes headlines; important details go below the fold. Take that 2023 USGS report, for example: Although 30% of the tap-water samples contained forever chemicals, at least half of the measurements fell below the lowest enforceable limits set in 2024. And results of nationwide monitoring, released in January 2025, suggest that PFAS contamination in public water supplies is actually much lower: With two-thirds of the monitoring complete, readings of PFAS that exceed EPA limits have been found in just 8% of small public water systems (those that serve fewer than 10,000 people) and 15% of large ones. That is not happy news, per se — it still represents millions of people — but it is far better than nearly half.

3. There is no perfect water filter. Leaving aside filters’ limited abilities — no filter removes all possible contaminants — every type has practical drawbacks, even those we recommend. And I hear from readers about it. Graeme, in New York City, was having trouble with his Claryum Direct Connect clogging. (“Replacing the filter three times in 90 days” gives you a taste of his frustrations.) Rob in Berlin wrote to me asking about reports of undersink filters causing catastrophic floods when they develop leaks.

We point out these and other weaknesses in our guides not only as something for you to know before you choose a specific filter but also because they’re weaknesses inherent to the entire category. Pitcher, under-sink, faucet-mount, whole-home, and reverse-osmosis filters all have at least one “genetic flaw,” be it high cost, limited capability, low flow, inefficiency, unreliability, or expensive upkeep. Often they have more than one. How much more frustrating would those things be if you were to learn that you never needed to use a filter to begin with?

I am not arguing against using water filters. They are one of my main focuses at Wirecutter, and all of my reporting goes into making recommendations that our readers can trust. Water quality is also a deeply personal concern, not something for me to adjudicate. I see my job as sharing as much information as I can, in as clear a manner as I can, to help you choose what’s best for you.

I stopped filtering my water not despite the fact that I’ve been reporting on water quality for a decade, but because of that experience. It took me that long to understand filtration well enough to be confident in my decision. My hope is that by gathering what I’ve learned here in one place, you will feel more confident in whatever decision you make.

Jan wrote in worried about an impending move to an apartment near the Gowanus Canal, New York City’s second-largest Superfund site. (I live a few minutes from the largest, Newtown Creek.) Environmental agencies have tested numerous sites in the neighborhood and noted places where contaminants need to be mitigated. “The construction has addressed soil vapor intrusion into the building,” Jan wrote. “We wanted to take precautions with potentially old water pipes leading into the building.”

I encouraged him to get the water tested before deciding whether to filter, and a few months later he wrote back. He had done a multi-contaminant at-home test, the kind where you dip test strips and compare them with a color chart. We don’t recommend such tests, because they can be difficult to interpret. Still, Jan’s mind was at ease: He had found elevated iron and copper (from the plumbing itself), as well as sulfates, but nothing of major concern.

“It looks good to me, particularly with none of the major scary ones registering, like lead or mercury,” he wrote.

This illustrates an important lesson: Proximity to pollution, even to polluted bodies of water, doesn’t mean your drinking water is dangerous. The USGS included a map in its summary of the famous 2023 PFAS study. It’s worth looking at.

The map doesn’t show an even scattering of PFAS sites across the US. It shows vast areas where no forever chemicals were found in the tap water at all. It shows a few regions of the country where, in clusters, multiple forever chemicals were found in the water from individual faucets. Most interestingly, it shows lots of faucets without any PFAS sitting near those with several types.

That’s a neat demonstration of how a lot of water pollution works. Something tangible — a factory, or a fuel depot, or a chemical spill — introduces a contaminant to the environment, creating a point source. The contaminant sinks into the soil or gets carried away by rainwater and enters the local aquifer or winds up in a reservoir. When a water utility later taps into the aquifer or reservoir, the contaminant has a new point source: the utility itself.

Often, the contaminant is removed during the water-treatment process, but if it isn’t, it flows to every home the utility serves. It doesn’t, however, go to any of the homes served by utilities that get their water from different, unaffected water sources, even those homes that are nearby on the map.

That’s a big reason why — even if, in aggregate, half the homes in the US are affected by forever chemicals — the risk isn’t 50-50 for everyone, everywhere.

This pollution pathway cuts both ways. The lead crises in Flint, Michigan, and Newark, New Jersey, showed how devastating it can be when an entire community is served by unsafe water.

On the other hand, in many US cities with the resources to maintain robust monitoring and treatment, utilities are delivering safe water to hundreds of thousands or even millions of people.

Not all water pollution works that way, of course. Sometimes the local geology creates a chronic problem, such as when it contains high levels of naturally occurring arsenic or radon. Older homes with lead pipes or lead-rich solder can become microsites for lead contamination, although many water utilities treat the water with corrosion inhibitors that keep the lead inert. Non-point sources — runoff from city streets, for example — contribute to the spread of low levels of contaminants over wide areas. And microplastics have become part of the global geology, as plastic waste degrades and spreads via air and water to every corner of the planet.

But for some of the most infamous contaminants — dioxane, benzene, hexavalent chromium, PCBs, PFAS — it’s often that pathway from the point source to the water supply system that brings problems.

Like Jan, reader Graeme got his water tested after I suggested doing that before buying a different, clog-resistant filter. He later sent a quick update: “It came back completely clear. You’ve saved me tons of time and money. NYC water continues to astound …”

It does. New York’s water is justifiably famous for its purity, and the city has gone to extraordinary lengths to keep it that way. But it isn’t the only city that can boast such a thing.

Consult your utility’s Consumer Confidence Report. Here’s New York City’s latest. Here’s Los Angeles’s report. Here are Chicago’s, Houston’s, and Philadelphia’s. You can usually find your CCR on your utility’s website; the EPA can help you find your utility if you’re unsure. (CCRs for the prior year are released as late as July 1, so you may find that yours is from two calendar years ago.)

A few terms to know: MCLG is the Maximum Contaminant Level Goal. It isn’t a requirement, but a level that the EPA or a state agency hopes to eventually achieve. MCL is the Maximum Contaminant Level that’s allowed by federal or state law. (And that brings up an important side point: under the Safe Drinking Water Act, states can set water-quality standards that are stricter than the federal ones. Several states were ahead of the EPA on PFAS limits before the Biden administration tightened the federal standards in 2024, for example. That’s worth remembering now that the Trump administration has rescinded or relaxed several of the standards and enforcement deadlines.)

THMs are trihalomethanes, and are mainly the by-product of disinfectants that are used to reduce bacteria and other pathogens in the water supply. Almost everybody’s CCR shows their presence at some level. How much is allowed is defined by the MRDL, the Maximum Residual Disinfectant Level; how much is aimed for is the MRDLG, the Goal. Most other listings are fairly self-explanatory: lead, mercury, and so on.

To know even more, use a home water test kit. It will tell you exactly what’s in your water, right where it comes out of your faucet. We recommend several Tap Score kits from SimpleLab, both for their ease of use — they come with prepaid and labeled packaging to help you ship your samples to the lab quickly — and for their clarity. The company explains the test results in plain language, flags anything of concern, and has support staff available to answer any questions you have.

I spoke with SimpleLab founder and CEO Johnny H. Pujol to understand what he has learned from a decade of water testing. He also shared a detailed summary of the data the company has collected.

A lot of people ask about PFAS and microplastics, Pujol said, “but the likelihood is that you’re going to spend a ton of money [on a test kit], and you may not find something that useful or interesting to your home.” (Testing for PFAS and microplastics requires two Tap Score kits in addition to the Advanced City kit that’s our top pick; they cost between $300 and $795.)

No PFAS chemicals are among the 10 most common contaminants that SimpleLab finds in either public (“city”) or private well water, according to the data Pujol shared. Two trihalomethanes — specifically chloroform and bromodichloromethane, both by-products of disinfection at the treatment plant — are among the top 10 in public water. Substances that come from the earth itself — zinc, barium, strontium, and sulfates — are in the top 10 in both city and well water. So is copper, leached from pipes in the home. Glyphosate, the active ingredient in Roundup and many other trademarked herbicides, shows up so rarely that when it does, Pujol said, “our data science team sends a message out — hey, we found a detection.”

And no PFAS are among the top 10 exceedances — instances where the level detected exceeded the company’s in-house health-guidance levels, which are based on EPA and other health-agency benchmarks. Chloroform, bromodichloromethane, and dibromochloromethane, all disinfection by-products, are the top three exceedances in public water supplies. Lead and arsenic are numbers four and five. For private wells, they are numbers one and two.

In terms of overall public health, Pujol worries that forever chemicals are drawing people’s focus away from where it is needed more urgently. “Here you’ve got a concentration that is almost comically low that gets widespread fear and interest — that’s PFAS,” he said. “Whereas the classics — arsenic, radon, lead, nitrate — they don’t seem to get the attention they deserve, and they’re much more significant.”

I didn’t know all of this before I got my water tested, but I knew enough about the US water system, and about my utility’s Consumer Confidence Reports, that I was confident the results would be fine.

Still, I got that little fist of nerves.

Having been president of my co-op in Queens, I was well aware that lead was likely to be present in the plumbing solder. And in New Jersey, there’s a chrome-plating shop — almost certainly a source of hexavalent chromium and other nasty stuff — a block and a half away from my house. Sure, it’s downhill, and sure, my water comes from a reservoir several miles in the other direction, and sure, the CCR showed nothing of concern. But.

So it was reassuring to get the results I expected.

I hated my pitcher filter long before I knew I didn’t need it. It would clog up any time a bit of rusty water came through the pipes, which, in a 70-year-old building with cast-iron service lines, was often. If you read reviews of pitcher filters — and reader comments on our guide to them — you’ll see the same problem mentioned over and over, by people all over the country.

If you do the same for the other filter types we’ve tested, faucet-mount and under-sink filters, you’ll see different common complaints. They’re hard to install. They deliver water slowly. (A kitchen faucet typically delivers 2.2 gallons of water per minute; these filters often cut that to half a gallon.) Replacement filters are expensive. Under-sink filters have a track record of catastrophic failures, leading to floods that have caused thousands of dollars in damage. Faucet filters can be damaged if you accidentally run hot water through them.

Reverse-osmosis filters, which we plan to test soon, are expensive and waste a lot of water (the filter needs frequent rinsing, and the rinse water goes right down the drain). Traditional reverse-osmosis systems take up most of the sink cabinet, because they work so slowly that the filtered water has to be stored in a tank. Tankless pumped reverse-osmosis is the hot new approach — but pumps can and do fail, as owner reviews attest.

As for Big Berkey–type countertop dispensers, not only do they tend to lack any kind of certification, but also their ultra-long-life filters are prone to bacterial and algal growth — like anything else that remains submerged for years at a time.

For me, such aggravations would be worth tolerating only if I was certain that my water needed filtering. But everybody has their own comfort zone on the risk-versus-certainty scale, so here’s a quick rundown of what our recommended filters can do.

• The Brita Elite pitcher filter is NSF/ANSI-certified for PFOA and PFOS, two of the most common forever chemicals; microplastics; lead, mercury, and cadmium; and several so-called emerging compounds that may be found in drinking water, including some pharmaceuticals. It is not certified for trihalomethanes (THMs), but it is likely good at removing them, because it uses activated carbon as one of the filter elements.
• The Pur Plus faucet filter is certified for lead, mercury, trihalomethanes (THMs), and numerous volatile organic compounds (VOCs) and emerging compounds. It is also certified for Particulate Class 1, which is a surrogate for microplastics. It is not certified for cadmium, PFOA, or PFOS.
• The Aquasana and A. O. Smith under-sink filters we recommend are certified for microplastics, lead, mercury, PFOA, PFOS, THMs and VOCs, and emerging compounds.

Whether those capabilities are worth the intrinsic headaches and the up-front and ongoing costs of filtration — worth more than the cost of a water test, at least — is a question that you have to answer for yourself. But I hope I’ve helped you come to your decision feeling a little more sure of the stakes.

This article was edited by Jen Gushue and Harry Sawyers.