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Mmmm, pesticides.

How to buy a water filter that actually filters out your local contaminants

By Zoë Schlanger

It’s very possible there are more unpleasant things in your tap water than you realize. Government watchdogs are slow to find them, and even when they do, it’s often too late. Even the fastest municipal responses to a water crisis take time, and by nature only happen once contaminants have been detected in the water, which is to say, likely only after residents have been exposed. For those interested in taking precautions, a water filter is the most direct solution. But not all water filters are created equal—in fact, there’s about a zillion different kinds.

Here’s how to pick one out.

Step One: Find out what the hell is in your water.

Get a quality report

The US Environmental Protection Agency requires your water supplier to mail you a water-quality report, also known as a “Consumer Confidence Report,” once a year. You can find these in an EPA database (or at least get a phone number to call to request one). But the Environmental Working Group, a health advocacy non-profit, has compiled roughly 28 million water records from nearly 50,000 American water utilities reports into an easier to use database here. The EWG database compares detected contaminant levels to state and national averages, as well as to health guidelines. It makes it pretty clear that in the US, most people are drinking water that is legally “safe” but isn’t actually risk-free. Every zip code turns up some form of contamination.

And of course, pay attention to public water supply notices. If your water supplier sends a letter, open it.

Check your pipes

In many cases, there may be nothing wrong with the water supply itself. The problem, if there is one, could be coming from your pipes. In the case of Flint’s ongoing lead crises, for example, the problem wasn’t that the water supply was leaded; it was that Flint’s service lines were made of lead, and the government failed to add enough anti-corrosion agent to the water. Follow these tips for checking if you have lead pipes in your home.

Older buildings may have sediment build-up in the pipes. This might not be technically dangerous, but it is kinda gross. A New York City plumber once showed me a quick way to check for sediment: Stop up your kitchen sink, fill it with water, and then darken the room (easiest to do this at night). Shine a flashlight at an angle into the water, and you should see any sediment. You can also momentarily drape a clean, unfolded sheet of paper towel over the surface of the water so it floats and lift it off carefully. Check the paper towel under a bright light for specks of material. Do either method shortly after filling the sink so the sediment doesn’t settle.

Step Two: Find out what else might be in your water

At the end of the day, a water-quality report will only take you so far. “The reality is, most contaminants are not tested for,” says Judith Enck, who served as a regional EPA administrator under President Obama.

Under the Safe Drinking Water Act, the EPA is responsible for determining when a chemical needs to be regulated in the US water supply, but it hasn’t added a new toxin to its list since 1996. (Even the Government Office of Accountability thinks that’s a sign of a broken system.)

Enck advises people to not expect the government to find something wrong with their water in a timely fashion. “Do not wait. Cobble the money together. Do the testing yourself,” she says. “You have to be a little bit of a detective. What might you be downwind from? Where is your public water near?”

One way to do this is to find out where your water supply comes from, and then look in its general vicinity on the EPA’s Toxic Release Inventory map to see what, if any, facilities are nearby, and what toxic materials they are permitted to release.

Citizen efforts have uncovered major emergencies in recent years. In Hoosick Falls, New York, for example, Michael Hickey knew his water wells were not far from a factory that manufactured Teflon. He bought several $400 testing kits, and sparked an investigation that uncovered major contamination from a chemical called PFOA that’s used in manufacturing Teflon. His town had likely been drinking PFOA in its water supply for decades. PFOA is not presently regulated by the EPA despite evidence linking it to heightened cancer risks, infertility, developmental delays, and other health problems. Ultimately, Hickey’s discovery led the area being declared a federal Superfund site.

A note about private wells

If your water comes from a private well, the government is not required to do any testing at all; that is entirely up to the homeowner. Homeowners will typically use these tests to look for naturally-occurring contaminants like arsenic and radon, depending on where you live, as well as bacteria (this is especially relevant if you have a septic system onsite, to be sure it isn’t leaching into your water supply). Check what any nearby manufacturing plant makes, and if it involves hazardous materials. If you live near a farm, testing for pesticides may also be advisable.

There are many ways to find water testing labs, and the Water Systems Council keeps a directory. If lead is your primary concern, some states offer free lead testing.

Step Three: Decide how big you want to go.

Do you live alone? You might opt for a pitcher filter. Are there five people in your household? An in-line system under your kitchen sink might make sense—or you could buy a refrigerator with a water filter built in. Are you willing (or permitted) to cut into your plumbing? Then a whole-house filter might be for you.

If you have done your due diligence in finding out what might be in your water and found no major red flags, the filter that comes with your refrigerator might be enough.

Step Four: Check which filter is certified for the contaminant most likely to be in your water

Contrary to popular belief, just buying whatever Brita pitcher is on the shelf in your local supermarket doesn’t always cut it. There is no one-size-fits all water filter; what you should buy depends on what’s in your water. (You can see what Brita does and doesn’t filter out here—only two of their products filter lead, for example).

In the US, look for certification from NSF International, a product-testing organization. Another tip, says Rick Andrew, director of water-systems development at NSF, is to check whether or not a product can be shipped to California. California has a rule that requires water filters that make health claims to register with the state as passing certification tests—so “if you see a product that isn’t shipping to California you might want to be wary,” Andrew says. (Wisconsin and Iowa have similar programs, but California is known to enforce theirs most.)

Also look for the NSF certification on the filter website or packaging to know that they’ve been through a testing protocol. The NSF has a slightly clunky database for checking which filters have passed their testing programs for each contaminant. Here are a few entries for common ones:

You can also search filters by manufacturer name here to see what they’re certified to remove.

The NSF operates a consumer info hotline, where they’ll talk you through questions about filters or contaminants in water:

  • +1800 673 8010

Another option is to use the Environmental Working Group’s water-filter database.

Step Five: Don’t get scammed.

Water-filter scamming is a big business—particularly refrigerator-filter replacement cartridges. The Association of Home Appliance Manufacturers (AHAM) says up to one-third of the filters in people’s homes are probably frauds. They’re often sold online with the exact same labeling as a legitimate filter—and may even bear the NSF seal, claiming to be certified.

One way to tell if a filter is counterfeit is the price: “If you try to order one and it’s like $5, and the one on the manufacturer’s site is like $50, that’s probably a fake,” says NSF’s Andrew. “If the deal seems too good to be true, it probably is.”

Some fake filters might be stuffed with newspaper or other useless material instead of the typical cake of activated charcoal. Even if the activated charcoal block is where it should be, they often don’t work as well, or for as long, in the knockoffs.

AHAM tested dozens of these, and found some worked for a short time at removing contaminants like lead or arsenic, but then failed far sooner than they should have. In some cases, they actually introduced contaminants into the water. Most of them clogged quickly, which can cause problems like flooding.

“Not only are these things not removing lead, some of these filters are leaching chemicals into the water. Actual manufacturers are using food-grade plastics. But the counterfeit plastics are just random white plastic,” says Jill Notini, the vice president of communications at AHAM.

Step Six: Change your filters!!!!

Seriously. Do it. If you don’t change your filter cartridge according to instructions, you might as well not bother getting a filter. They don’t work as intended after whatever time period they’re certified for. This is for very reasonable physics reasons; contaminants will built up in the cartridge until the cartridge can’t hold any more.

Skeptical? Here’s why you should care

In 2018, large parts of the US woke up to the fact that water contamination is a widespread problem. The country had been building to this for a while: The Flint, Michigan lead-contamination crisis is in its fourth year. The lead crisis in Chicago’s East Side broke in 2016. This year, Newark, New Jersey added itself to the list of major urban lead emergencies. Lead is known to impact children at lower doses than adults—and there is no safe level of lead in drinking water.

But lead is far from the only villain, as far as water contaminants go. Slowly but surely, PFAS is becoming a household name and emerging as the DDT of this generation. Compounds that fall under the PFAS umbrella—like PFOA (the Teflon ingredient) and PFOS (used in firefighting foam)—have cropped up in water supplies in West Virginia, New York, Michigan, Illinois, Pennsylvania, and Wisconsin. Martha’s Vineyard, the ritzy island community off of Massachusetts, is the latest US municipality to be added to the lengthening PFAS contamination list.

And then there are the trihalomethanes: These are byproducts of the chlorination process that include chloroform and have been linked to a number of health problems.Towns in US states like New York, Florida, Michigan, and Canadian provinces like Newfoundland and Labrador all found high levels of trihalomethanes in their municipal water this year.

As contamination sites proliferate, water users are growing wary—but few are changing anything about the water they drink. According to a survey by NSF, the group that certifies water filters, 71% of people in the US drink tap water, and 55% are concerned about what might be in it—but 42% don’t take any steps to do anything about it. But hey, it’s about to be a new year, when everyone musters the will to achieve tedious but beneficial things. And like they say: Nothing changes if nothing changes. So maybe go get yourself a filter.