National register · 20,673 water systems on file
What's in your tap water?
I compile what U.S. water utilities report in their own annual Consumer Confidence Reports: lead, PFAS, nitrate, arsenic, disinfection byproducts, chlorine and more. Pick your state below and you'll see what your utility found — and what, if anything, that justifies buying.
Coverage is partial and uneven: some states have dozens of systems on file, others only a handful. If yours is missing, your utility still has to send you its report every year.
Testing station
What's in your tap water?
Enter your ZIP code and I'll pull up what your own water utility reported, straight from its annual Consumer Confidence Report.
The limits, without the jargon
Federal rules use two kinds of threshold, and confusing them changes everything. An MCL — Maximum Contaminant Level — is enforceable and protects health: going over it obliges the utility to act and to tell its customers. A secondary standard (SMCL) is advisory and covers taste, color and staining: going over it is a comfort problem, not a health risk.
So on city pages I keep the top of the scale for enforceable limits. Going over a secondary standard never turns red.
- Nitrate
- limit 10 mg/L
- Comes mostly from farm fertilizer and septic systems. The limit exists above all to protect infants and pregnant women.
- Lead
- limit 15 ug/L
- Measured at the tap. Most lead comes from your own service line and household plumbing, not from the treatment plant — which is why the number varies house to house.
- Copper
- limit 1.3 mg/L
- Leaches from copper pipes and brass fittings, especially where the water is corrosive. Gives water a metallic taste and can stain fixtures blue-green.
- Arsenic
- limit 10 ug/L
- Occurs naturally in bedrock across much of the West and Midwest. Long-term exposure is the concern, not a single glass.
- PFOA
- limit 4 ng/L
- "Forever chemical," measured in parts per trillion. Testing is recent and still uneven: no measurement does not mean no PFAS.
- PFOS
- limit 4 ng/L
- The other "forever chemical" with a federal limit, alongside PFOA. Reverse osmosis is the household treatment that reliably removes both.
- Disinfection byproducts (TTHM)
- limit 80 ug/L
- Formed when chlorine reacts with natural organic matter in the source water. The most commonly exceeded federal limit in the country.
- Disinfection byproducts (HAA5)
- limit 60 ug/L
- Haloacetic acids — the other family of byproducts formed when chlorine meets organic matter. Reported alongside TTHM in nearly every report.
- Fluoride
- limit 4 mg/L
- Often added on purpose, around 0.7 mg/L, to prevent tooth decay. The federal limit sits far higher, at the level where long-term exposure affects bones and teeth.
- Turbidity
- limit 1 NTU
- How cloudy the water is. A sudden rise usually means something happened on the distribution system.
- pH
- secondary 6.5–8.5 pH units
- How acidic the water is. Outside the range it goes after your pipes rather than the people drinking it — which is how lead gets into the water.
- Total dissolved solids
- secondary 500 mg/L
- Everything dissolved in the water, minerals included. High TDS tastes flat or salty; very low TDS means very soft water.
- Sodium
- secondary 20 mg/L
- Worth watching on a low-sodium diet. A salt-based softener adds sodium in proportion to the hardness it removes — which is exactly the trade-off to weigh before buying one.
Hardness: four bands, no standard at all
Scale has neither an MCL nor a secondary standard: very hard water is perfectly safe to drink, and the calcium is arguably good for you. The 7 grains per gallon mark is not a health standard — it is the point where a softener starts paying for itself. Note that most utilities never report hardness at all, precisely because nothing requires them to.
- Soft water
- 0 to 3.5 gpg
- No softener needed.
- Moderately hard water
- 3.5 to 7 gpg
- A softener is optional here — keep an eye on your water heater element.
- Hard water
- 7 to 10.5 gpg
- A softener is worth it to protect your appliances and fixtures.
- Very hard water
- over 10.5 gpg
- A softener is strongly recommended: scale is already shortening the life of your appliances.
Water in the biggest cities
Browse by state
Tested by
Rachel, independent tester
I publish what each city's own water utility reports, and I measure what actually runs through my house: hardness and chlorine before and after, TDS, salt bags counted, flow rate, taste. The raw numbers, including when they are bad. For models I have not had my hands on, I compare the specs, and I say so plainly on the page.
- Gear bought, never loaned
- Measurements, not impressions
- No brand pays to appear here