Research, explainers, and practical guides that connect public water evidence to the questions households actually ask.
28 published articles6 disciplines180 cited source recordsLatest 2026-11-04
EPA's 2024 sampling found a PFOS sample above the new 4.0 ng/L limit in 746 monitored cities. Here is what the records show and how to read them.
A well bacteria test costs about $14 to $40 at public labs, a basic package $60 to $70, and a broad package up to $450. Real 2026 prices from state and university labs, and what to test for.
Radon is a radioactive gas that can dissolve into well water, mostly in granite areas. Most of the risk comes from breathing it as it leaves the water. How to test and treat it.
A water softener removes the minerals that cause scale. A water filter reduces the contaminants it is certified for. What each one does, what it can't do, and how to choose.
A consumer confidence report is the yearly water quality report your utility must send by July 1. Here is what it contains, how to read its table, and what it can't show.
Coliform is a warning sign, not usually the germ itself. What a positive well test means, what to do first, and when to test again.
Small lab studies link hard water to mineral buildup on hair and, in some, weaker strands. None has measured hair loss in people. What each one found.
Hard and soft water differ in calcium and magnesium, not in health limits. What changes at home, what research says, and when a softener or filter fits.
Five ways to check your hardness, from the signs at your sink to your utility's report and a home test, plus how to read the number you get.
Lead usually comes from your home's own pipes, not the utility. That changes which filter you need and where you put it. A plain comparison.
Pitcher, countertop, under-sink or whole-house? A plain comparison of the filter formats, where a PFAS certification applies, and which situation each one fits.
Federal monitoring recorded lead above the 15 µg/L action level at 18 water systems that serve a city in PurityMap’s reports. Here is what that number means, and what it does not.
Arsenic in private wells usually comes from rock, not pollution, and you can't see, smell or taste it. How to test your well, read the result against the limit, and treat it.
Hard water is a comfort and plumbing issue, not a health one. Here's how to read your hardness number and decide whether a softener is actually worth it.
The Purity Score is one number from 0 to 100 — but only for the contaminants a system actually measured. Here's how it's built, and what it deliberately leaves out.
Your utility's record stops where your plumbing starts. How to choose a screening kit or a lab test, what to test for, and how to read the result.
The systems serving the most Americans span a wide range of Purity Scores. Size isn't a quality signal — here's what the biggest US water utilities' records actually show.
Nitrate reaches wells from fertilizer, septic systems and manure, and it matters most for babies under six months. How to test every year, read the result and treat it.
Tucson Water serves 732,906 people from groundwater. Here's what the EPA's 2024 PFAS round and the latest lead monitoring actually recorded — and what's still pending.
The cities at the top of our Purity Score ranking all sit at 100/100 — but a perfect score means something narrower than it sounds. Here's how to read the list.
A 'non-detect' is one of the most misread words on a water report. It does not mean zero. Here is what it actually means.
Carbon suits taste, chlorine and certified lead reduction. Certified reverse osmosis covers a wider range and usually costs more. Compare what each removes and costs.
Hard water is a plumbing and comfort issue, not a health one. Here is how to read hardness and decide whether a softener is worth it.
The disinfectant that keeps waterborne disease rare also creates by-products. Here's how to think about that balance instead of fearing it.
What a low Purity Score does (and does not) tell you, and how to read our national rankings without drawing the wrong conclusion.
Which filters reduce lead, PFAS, arsenic and nitrate? Match the technology and the certification to your actual finding, not to marketing.
A system can report 'below the action level' and your kitchen tap can still have lead. Here is how lead reporting actually works and what to do about it.
In 2024 the EPA set the first enforceable national limits on PFAS 'forever chemicals.' Here is what they are, what EPA proposed in May 2026, and what to do if PFAS is detected in your water.
Journal analysis adds context; it does not replace a water-system report, source document, ranking methodology, or certified household test.