Is tap water safe to drink?

In the US, tap water is regulated, but regulated does not mean nothing gets through, or that your particular tap matches the citywide average. The gaps are specific: newer contaminants like PFAS that the rules are still catching up to, and whatever your own home's pipes add. That is why testing your own water beats assuming, in either direction.

Do water filters remove PFAS?

The good ones do. Reverse osmosis removes PFAS well, and activated carbon or ion-exchange filters certified for PFAS (look for an NSF/ANSI listing for PFOA and PFOS, such as P473) also work. A basic pitcher not certified for PFAS may not.

Does boiling water remove contaminants?

It kills germs, not chemicals. Boiling does nothing for PFAS, lead, arsenic, or nitrate, and can slightly concentrate them as water evaporates. Use it for microbes on a boil-water notice, not for filtration.

Is bottled water cleaner than tap?

Not reliably. Bottled water often contains more microplastics than tap, is regulated as a food rather than to drinking-water standards, and is sometimes just filtered municipal water in a plastic bottle.

Do I need reverse osmosis, or is a Brita-style filter enough?

It depends on your water. A certified carbon pitcher handles chlorine, taste, and, if certified, lead and some PFAS, which is enough for many people on city water. Reverse osmosis is worth it for a well, or for dissolved contaminants like arsenic, nitrate, or fluoride that carbon does not remove.

Does a fridge or pitcher filter remove lead?

Only if it is certified to (NSF/ANSI 53 for lead). Many basic filters are certified only for taste and chlorine (NSF 42), not lead, so check the packaging rather than assume.

How do I find out what's in my water?

Start with your utility's annual water quality report (free, online or mailed) and the EWG Tap Water Database for your zip code. For lead, an older home, or a private well, use a certified mail-in water test, since those are not captured by the utility report. Tap Score sells kits matched to your source, for city tap water and for well water (affiliate links).

Is fluoride in tap water bad for you?

It is debated, and plenty of people choose to filter it out. Fluoride is added to reduce tooth decay, but the safety concerns are real: higher exposure causes dental and skeletal fluorosis, and a 2024 US government review found, with moderate confidence, that exposure above about 1.5 mg/L (more than double the level added to US water) is linked to lower IQ in children. A federal court has since ordered the EPA to address fluoride's neurotoxicity risk. The strongest evidence is at exposures above what most US systems add, but the science is active and unsettled, so wanting it out of your water is a reasonable call. Reverse osmosis removes it.

Does reverse osmosis remove minerals I need?

Yes, it strips beneficial minerals like calcium and magnesium along with the contaminants. For most people eating a normal diet that is a minor issue, and many reverse osmosis systems add a remineralizing stage that puts some back.

Are microplastics in tap water dangerous?

They are widespread, including in bottled water, and turn up in human tissue, but the health effects are not yet established. The sensible, low-cost steps are drinking less from single-use plastic bottles and, if you want to reduce them further, filtering with reverse osmosis or fine filtration.

What is the healthiest or best water filter?

There is no single "healthiest" filter, and any list that crowns one is usually ranking brands, not matching your water. The most thorough removal is reverse osmosis, but for many people on treated city water a certified carbon pitcher covers it. Find out what is in your water, then buy a filter certified to remove it. Read the NSF/ANSI certification, not the marketing.

Is reverse osmosis water safe, or bad for your kidneys?

It is safe to drink. Reverse osmosis does strip out beneficial minerals like calcium and magnesium along with the contaminants, but for anyone eating a normal diet that is minor, and many systems add a remineralizing stage. There is no good evidence that reverse osmosis water harms your kidneys.

Are pitcher filters like Brita worth it?

For what a basic carbon pitcher is built to do, yes: it cuts chlorine and improves taste cheaply. The catch is it only removes what it is certified for. A standard pitcher does not reliably remove lead, PFAS, arsenic, or nitrate unless the label says so, which is why some people move to a certified lead or PFAS pitcher, or to reverse osmosis. Check the certification, not the brand.

Do water filters actually work, and what are the drawbacks?

A filter certified by NSF/ANSI removes what it is certified for. The drawbacks are cost, replacing cartridges on schedule, the wastewater reverse osmosis makes, and the false confidence an uncertified filter can give you. The failure mode is rarely filters not working; it is buying one that was never tested to remove your contaminant.

Do water filters remove bacteria and parasites like Cryptosporidium or E. coli?

Most filters are built for chemicals, not microbes, so many do not. For parasites like Cryptosporidium and Giardia, look for cyst reduction (NSF/ANSI 53), an absolute one-micron filter, or reverse osmosis. Boiling reliably kills them. This matters most on well water or during a boil-water notice; treated city water is disinfected against these already.

How often should I change my water filter?

On the manufacturer's schedule, which depends on the filter and how much water you run through it. A spent cartridge stops removing contaminants and can release some of what it trapped back into your water, and an old, damp filter can grow bacteria. An overdue filter can be worse than none.

Can hot water damage a water filter?

Yes. Carbon filters and reverse osmosis membranes are made for cold water, usually rated to about 100°F, and warmer water both reduces how much they remove and can permanently damage an RO membrane. This is worth thinking about if your water runs hot, for example where pipes cross a hot attic in summer. An under-sink RO is the hardest case, because it refills from the line automatically and cannot wait for the water to run cold. A countertop unit you fill by hand avoids the problem: run the tap until it is cold, then fill it. If you prefer under-sink, insulate the cold-water lines and check the system's maximum inlet temperature before buying.

Is Your Tap Water Safe? What's In It, and How to Filter It

US tap water is regulated and mostly safe, but specific contaminants slip through. What is actually in your water, how to find out, and how to choose a filter that removes what matters.

Category environmental

Reading Time 13 min

Sources 7 cited

Last Updated September 2026

See the filters we recommend by what is in your water

Regulated does not mean pure

Public water in the US is regulated. The EPA sets enforceable limits on scores of contaminants, and utilities report on what they find every year. But regulated is not the same as pure, and it is not the same as knowing what is in the water at your particular tap.

Two things fall through the gaps. First, the rules do not yet cover everything: some of the contaminants people worry about most, like PFAS (the "forever chemicals") and microplastics, are newer than much of the framework, and the limits are still catching up. Second, what leaves the treatment plant is not always what reaches your glass, because your local source and your home's own pipes each add their own story. So this guide is not about whether to trust the water in the abstract. It is about finding out what is in yours, and fixing the specific things worth fixing.

What's actually in your water

Two contaminants get most of the attention right now, and both deserve it. Then there is a set of older, better-understood ones that can matter just as much, depending on your water.

PFAS, the "forever chemicals"

PFAS, short for per- and polyfluoroalkyl substances, are a large family of synthetic chemicals used to make things nonstick, waterproof, and stain-resistant, and to make firefighting foam. They earn the "forever chemicals" nickname from a carbon-fluorine bond that barely breaks down, so once they reach groundwater they stay, and they build up in the body over years. They are detectable in a large share of US water systems.

The health findings are mostly observational, but consistent: higher PFAS levels track with higher cholesterol (including LDL and ApoB), thyroid changes, a weaker antibody response to vaccines, and certain cancers ^[1]. The evidence was solid enough that in 2024 the EPA set its first enforceable national limits for several PFAS, capping the two most-studied, PFOA and PFOS, at 4 parts per trillion ^[2]. That is an extremely low limit, and it reflects how little PFAS is now considered safe. PFAS are removed by reverse osmosis, by distillation, and by carbon or ion-exchange filters certified for them. Boiling on its own does not remove them: a distiller works because it captures and recondenses the steam and leaves the PFAS behind, but a pot on the stove just concentrates them as the water evaporates.

Microplastics

Microplastics are tiny fragments shed from packaging, textiles, and the slow breakdown of larger plastic. They are in tap water, and often in greater numbers in bottled water ^[3]. They have turned up all through the human body, from blood and lungs to the placenta and even the brain ^[4]^[5].

What they do to health is still being worked out. We know they are widespread and inside us, and we do not yet know the dose that matters. That uncertainty is not a reason to panic or to ignore it. Reverse osmosis and fine filtration catch most of them, and the simplest near-term win is drinking less from single-use plastic bottles, which are a bigger source than most tap water.

The established ones

None of the contaminants below are new, but if they are in your water, they are among the most serious risks here.

Contaminant	Where it comes from	The concern	Best removed by (NSF/ANSI)
Lead	Old lead pipes, solder, and brass fixtures, so it is added by your home, not the source	Neurotoxic with no safe level ^[6], worst for children and pregnancy	Reverse osmosis, or a lead-certified carbon block (NSF 53 or 58)
Arsenic	Naturally in some groundwater, mainly private wells and certain regions	Cardiovascular disease, several cancers, skin changes	Reverse osmosis, distillation, or arsenic-rated media (NSF 53 or 58)
Chlorine and its byproducts	Chlorine is added to disinfect; byproducts (trihalomethanes) form when it meets organic matter	Disinfection prevents serious waterborne disease; byproducts carry a small chronic-exposure risk	Activated carbon (NSF 42, or 53 for byproducts)
Nitrate	Fertilizer and manure runoff, septic systems, mostly in wells	Dangerous for infants; a marker of agricultural contamination	Reverse osmosis or nitrate-selective ion exchange (NSF 58)
Fluoride	Added to about two-thirds of US water for dental health	Reduces tooth decay, but higher exposures are linked to lower childhood IQ and to dental and skeletal fluorosis	Reverse osmosis or distillation (NSF 58)

Two of these deserve a note. Lead is the one case where the problem is almost always your own plumbing rather than the water source, so a citywide report can look clean while your tap is not. If you live in an older home, run the cold tap for a bit before drinking, never cook with hot tap water, and test at your own faucet. And fluoride is the one people argue about. It reduces tooth decay, which is why it is added, but the concerns are real and depend on the dose: higher exposure is linked to dental and skeletal fluorosis, and a 2024 US government review concluded, with moderate confidence, that exposure above about 1.5 mg/L, more than double the level added to US water, is associated with lower IQ in children ^[7]. That has pushed fluoride into active regulatory debate. Whether to filter it out is a reasonable personal call.

One category this guide mostly sets aside is microbes: bacteria and parasites like Cryptosporidium, Giardia, and E. coli. On municipal water they are rarely the issue, because keeping them out is exactly the job disinfection does, and it does it well. They matter most on private well water, which no one disinfects for you, and during a boil-water notice, when the usual treatment has failed. Boiling handles them, as do filters rated for cyst reduction and reverse osmosis.

Find out what's in your water

This is the step most people skip, and it is the one that saves you money and worry. You do not need to guess, and you should not buy a filter until you know what you are filtering.

Read your utility's yearly report. Every US public water system publishes an annual water quality report, sometimes called a Consumer Confidence Report, online or mailed to you. It lists what was detected in the municipal supply. It is a good baseline, but remember it describes the plant, not your tap.
Look up your zip code. The EWG Tap Water Database turns your local system's data into plain language, contaminant by contaminant.
Know what those miss. Lead and copper come from your home's pipes and fixtures, so only a test at your own faucet catches them. And private wells are not covered by any utility report at all; if you are on a well, testing is entirely on you.
Use a mail-in test when it is warranted. A certified lab sends a kit, you return a sample, and you get a real contaminant panel. An at-home service like Tap Score sells targeted kits for city tap water and for well water, so you can match the panel to your situation. It is worth it if you are on a well, live in an older home, or your report flags something. Test for what is plausible where you live rather than paying for everything.

Test first, then filter for what you find

An at-home kit sends you a certified contaminant panel for your actual tap. The filters are the two below: a certified carbon pitcher covers most people on treated city water, and countertop reverse osmosis is the answer to a well or a known dissolved contaminant.

City water test → Well water test → Carbon pitcher → Countertop RO →

These are affiliate links: we may earn a small commission at no extra cost to you, and it never changes what we recommend.Full disclosure →

How to choose a filter

Once you know your target, choosing is straightforward, and the single most important rule is this: a filter is only as good as the specific certification it carries. "Reduces contaminants" on a box means nothing on its own. What you want is an NSF/ANSI number, an independent standard that spells out exactly what a filter has been tested to remove. Match the standard to the contaminant you have.

One distinction does most of the work here, and the wording on the box is where brands hide. Certified to a standard means an accredited body audited the product and lists it publicly: NSF itself, or WQA, or IAPMO, which are equals. Tested to a standard means the company paid a lab once and is quoting the result. The second is not worthless, but it is the company's own homework, and some well-reviewed filters are certified only for chlorine while their lead and PFAS claims rest on testing alone. Check which claim carries which word.

NSF/ANSI standard	What it certifies
42	Aesthetic effects: chlorine (taste and odor) and particulates
53	Health contaminants: lead, many VOCs, chromium, and microbial cysts
58	Reverse osmosis systems: a broad list, including arsenic, nitrate, fluoride, and lead
62	Distillation systems: metals, fluoride, nitrate, and more
401	Emerging contaminants: pharmaceuticals, pesticides, and similar trace compounds
P473	Retired. PFOA and PFOS reduction moved into 53 for carbon filters and 58 for reverse osmosis, so that is where to look for a PFAS claim now. You will still see P473 printed on packaging and it is not a lie, just dated. A 2022 revision went further, adding a broader total-PFAS claim and cutting the allowed limit from 70 to 20 parts per trillion, so a recent certification means more than an old one.
372	A different kind of standard: not what the filter removes, but that the product's own wetted parts are "lead-free" and do not leach lead into your water (often paired with NSF/ANSI 61 for material safety)

The main types, roughly in order of how much they remove:

Activated carbon (pitcher, faucet, fridge, or countertop). The cheap default, and for many people on treated city water, enough. It removes chlorine, improves taste and smell, and cuts many organic chemicals; a good carbon block certified for it also reduces lead and some PFAS. It does not remove most dissolved minerals, nitrate, arsenic, or fluoride.
Reverse osmosis (under-sink or countertop). The broadest removal there is, forcing water through a membrane that strips PFAS, arsenic, lead, nitrate, fluoride, and microplastics. It comes in a few forms: a plumbed under-sink system, either with a storage tank or a tankless version that makes water on demand with an electric pump and frees up cabinet space; or a countertop unit you fill by hand that needs no installation, which is handy for renters or anyone who does not want to modify plumbing. Either way the trade-offs are real: it wastes some water, it is slower than a carbon filter, and it removes beneficial minerals along with the bad, though many systems add a remineralizing stage. This is the right tool for a well, a known dissolved contaminant, or simply wanting the most thorough option.
Distillation. Boils water and recondenses it, leaving almost everything behind. Thorough, but slow, energy-hungry, and flat-tasting.
Whole-house (point of entry). Treats every tap for sediment and chlorine, which is good for smell and for protecting appliances, but it is usually not the tool for lead or PFAS at the drinking tap. Those are better handled at the sink.

Whatever you choose, replace the cartridge on schedule. A spent filter stops working and can end up worse than none.

Test first, then filter for what you find

City water test → Well water test → Carbon pitcher → Countertop RO →

These are affiliate links: we may earn a small commission at no extra cost to you, and it never changes what we recommend.Full disclosure →

What won't help

Boiling kills germs, not chemicals. It matters on a boil-water notice, but it does nothing for PFAS, lead, arsenic, or nitrate, and as water evaporates it can slightly concentrate them. A countertop distiller is the exception, and only because it does more than boil: it captures the steam and recondenses it, leaving the contaminants behind.
Bottled water is not automatically cleaner. It often contains more microplastics than tap, is regulated as a food rather than to drinking-water standards, costs far more, and is sometimes just filtered municipal water in a plastic bottle.

The bottom line

You do not need to panic-buy a whole-house system. The move is smaller and smarter: read your utility's report and/or test your own tap, find the specific things worth removing, and match a certified filter to them. For many people that is a certified carbon pitcher and nothing more. For a well or a known contaminant, reverse osmosis earns its place. Reducing a real exposure like PFAS is one of the few environmental levers you fully control, and it supports the same markers, like ApoB and LDL cholesterol, you are probably already working on.