I'm Wirecutter's Water-Quality Expert. I Don't Filter My Water

Summary

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 That’s worth remembering now that the Trump administration has rescinded or relaxed several of the standards and enforcement deadlines.)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...