How to decide whether you need a water filter

Summary

In much of the United States, the basics of tap-water safety come from regulations and treatment at the public-system level, experts say. The Environmental Protection Agency sets health standards for more than 90 contaminants in public water systems under the Safe Drinking Water Act, and utilities disinfect water—often with chlorine—to kill germs before it reaches homes. That is why many experts say most households do not need extensive treatment at home.

UCLA’s Gregory Pierce, director of the University of California Los Angeles’ Human Right to Water Solutions Lab, said that unless people are experiencing health impacts, have received a notice from their water system, or are responding to a credible report that their water is unsafe, they should not feel compelled to buy a filter. Pierce also said a filter can still make water taste “a little bit better,” but it “shouldn’t be considered necessary” in most of the country.

Pierce’s guidance fits the basic idea that the need for filtration depends on what is actually in a household’s water and why a resident is concerned. Water quality can vary between buildings, even within the same broader service area, because utilities are generally only responsible for the water until it reaches private property. For many residents, that gap can be addressed by checking what the local system reports and then deciding whether a further step—such as sampling—is warranted.

A practical starting point, according to the AP report, is the utility’s annual Consumer Confidence Report, which details detected contaminants and whether the system meets federal standards. The report is typically posted on city or utility websites, and residents can also contact their water provider directly with questions. Jess Goddard, chief science officer at environmental testing company SimpleLab, said consumers “should probably test your water to identify if you have a risk that you need to treat.”

For private wells, experts say the responsibility shifts to homeowners. Private wells are not regulated under the Safe Drinking Water Act, and people relying on them may need to arrange their own monitoring. The EPA is among the agencies offering resources for private-well owners, and testing kits can cost a couple hundred dollars or more depending on the contaminants the kits screen.

Experts also outlined how water testing typically works: a consumer orders a kit, collects a sample according to the instructions, and mails it to a certified lab, which analyzes it for specific contaminants. Labs can test for a range of concerns, including PFAS, microplastics, metals, and disinfection byproducts. If testing shows a serious problem, Pierce recommended contacting the water utility or the state environmental agency for guidance; in cases where contamination is high, officials may recommend options that go beyond an inexpensive household filter, such as temporary alternative water sources or infrastructure upgrades like pipe replacement.

If no serious issue is identified, a household filter may still help for targeted goals. The EPA advises that many household activities do not require treatment, and the focus for filtration is often drinking and cooking rather than tasks such as flushing toilets or washing clothes. When selecting a device, the AP report pointed to NSF and American National Standards Institute ratings that indicate what different filters can reduce, with common NSF/ANSI ratings including 42 for taste or smell concerns, 53 for health effects, and 401 for emerging compounds. Sydney Evans, a science analyst who led a water filter testing project at the Environmental Working Group, said “not every filter is good for everything” and suggested that even if a filter claims broad capabilities, people may not need it.

In addition to safety questions, experts said many households use filters for taste or odor and want confidence in the water’s sensory qualities. Goddard said those factors “really do impact people’s enjoyment or sense of confidence in their drinking water,” and he described basic carbon filters—like many pitcher models—as potentially effective. Carbon-based filtration can reduce chlorine and byproducts formed when chlorine reacts with natural organic matter in water.

Even when contamination levels are below federal limits, SimpleLab analysts told the AP report that some consumers still filter their tap water to reduce long-term exposure. Samantha Bear, a senior research analyst at SimpleLab, said her team filters their own tap water “not because the water is unsafe,” but to reduce long-term exposure. The report also noted that PFAS concerns can come up even in places without high local PFAS levels; the EPA says filters can reduce PFAS levels, but it urges consumers with concerns to contact their local water provider first.

Lead is another issue where experts said filtration may be considered, even though filtration alone may not solve the underlying cause. The EPA notes that no level of lead is safe, and the AP report said people may use filters where alternatives or pipe replacement are not recommended.

Different systems treat water in different ways. The AP report described point-of-use setups—including pitchers, refrigerator filters, and faucet-mounted systems—as treating water where people drink or cook with it, while under-sink and reverse osmosis units also treat at the tap but may require professional installation. Whole-home systems filter at the point of entry, meaning water is treated before it moves through a house’s plumbing; the report said these systems are typically more expensive, often require professional installation, and are generally used for issues that affect all household water, such as hardness or high iron.

The report also said some homes use water softeners to reduce minerals that can build up in plumbing, though softeners do not remove most other contaminants. Less common are distillation systems, which boil water and condense steam to remove minerals and some contaminants. Experts said most households do not need whole-home or distillation systems unless there is a specific, documented issue.

Finally, maintenance matters. Experts warned that filters can lose effectiveness or allow bacteria to build up if cartridges are not changed according to manufacturer instructions, with Pierce saying that otherwise filters may “do more harm than good.”