Updated April 2026 · EPA SDWIS data
Drinking Water Blog
Data-driven analysis of U.S. drinking water quality, sourced from the EPA Safe Drinking Water Information System and supported by the EWG Tap Water Database. Articles cover specific contaminants (lead, PFAS, microplastics), ranked system lists, filter and treatment guides, and how the federal regulatory framework actually works.
What the IsWaterSafe Blog Covers
U.S. drinking water reporting sits in a confusing middle ground. The Safe Drinking Water Act sets enforceable limits, but those limits are negotiated between health science and treatment cost — they are not the same as EPA's non-enforceable health-based goals. State agencies enforce the rules under EPA primacy with widely varying capacity. Utilities publish annual Consumer Confidence Reports written for compliance rather than comprehension. And household plumbing introduces contamination downstream of any utility-side reading.
The blog organizes coverage into four threads: contaminant deep dives (what each substance is, where it comes from, what removes it), ranked system lists drawn from EPA data, how-to guides for individual residents, and policy explainers when federal rules change. Articles are dated, sourced to public datasets, and re-checked against the underlying records on each refresh.
Contaminant
Per-contaminant deep dives — what the substance is, where it comes from, what the EPA Maximum Contaminant Level is, what the non-enforceable health-based goal (MCLG) is, and which treatment technologies actually remove it.
Microplastics in Drinking Water: What the Data Shows (2026)
EPA proposed first-ever monitoring rules for microplastics in 2026. What we know about microplastic contamination in tap water and how to reduce exposure.
Lead in Drinking Water: 9.2 Million Lead Pipes Still in Use
There is no safe level of lead in water. EPA data shows which systems have lead violations, how lead enters tap water, and what filters remove it.
PFAS in Drinking Water: Which Systems Are Affected
PFAS "forever chemicals" in US drinking water, which systems have PFAS violations and what residents should know.
Ranking
Ranked tables drawn directly from the EPA Safe Drinking Water Information System — not editorial picks, not utility-supplied numbers.
Guide
Step-by-step how-to coverage — checking your tap, reading your utility's Consumer Confidence Report, choosing an NSF-certified filter, requesting test data from your local water authority.
How These Articles Are Researched
Every violation count, contaminant detection, and enforcement action links back to a public federal dataset. Violations come from the EPA Safe Drinking Water Information System. Contaminant MCLs and MCLGs come from EPA's National Primary Drinking Water Regulations. Treatment efficacy claims cite NSF/ANSI standards. Read the full IsWaterSafe methodology for how the score, rankings, and contaminant joins are computed.
Frequently Asked Questions
How is "safe" defined for drinking water?
Under the Safe Drinking Water Act, EPA sets a Maximum Contaminant Level (MCL) for each regulated contaminant — the legally enforceable limit a public water system must stay below. EPA also publishes a non-enforceable Maximum Contaminant Level Goal (MCLG) that reflects health-based targets, which for several contaminants (including lead and PFOA/PFOS) is zero. Articles on IsWaterSafe report both numbers when relevant so the gap between "legally compliant" and "health-based goal" is visible.
How are these articles updated?
EPA refreshes the Safe Drinking Water Information System on a quarterly cycle, and IsWaterSafe re-runs every ranking and contaminant article against the new file when it ships. Articles also get revised when material federal rule changes occur — for example, the April 2024 PFAS National Primary Drinking Water Regulation triggered a refresh of every PFAS-related article. Each piece carries a published date; the master refresh date is April 2026.
Is IsWaterSafe giving health advice?
No. IsWaterSafe describes what the EPA data shows. It does not diagnose any health problem, recommend a specific treatment, or rule out a concern in your household. An MCL exceedance is a regulatory event, not a clinical diagnosis. If you have a specific concern (an immunocompromised household member, a pregnancy, an infant on tap-water formula, a recent lead exposure), talk to your physician and contact your local public health department.
Why do nearby systems have very different grades?
Source water (deep protected aquifer vs. surface reservoir downstream of agriculture), distribution-network age, lead service line prevalence, treatment chemistry, and operator capacity all move the score. Two systems in the same metro can score very differently for any of these reasons. The "Cities with the Worst Drinking Water" article and the per-system pages explain which factor dominates each system.
Can a home filter actually remove lead and PFAS?
Yes, but only if it is certified for that specific reduction. NSF/ANSI Standard 53 certifies filters for lead reduction; NSF/ANSI 401 and P473 certify products for emerging contaminants including PFOA and PFOS. Activated-carbon pitchers without these certifications often do not meaningfully reduce lead or PFAS. The "Is My Tap Water Safe" guide explains how to read NSF certifications on a filter package.
Sources: EPA Safe Drinking Water Information System (SDWIS), EPA National Primary Drinking Water Regulations, EWG Tap Water Database. SDWIS and EPA regulations are U.S. government public domain. Cite as: "IsWaterSafe, April 2026 reading. Data: EPA SDWIS."
Last updated 2026-04-04 · 5 articles published.