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Nampa, ID · 104,746 people served · EPA data 2021–2026

Tap water quality in Nampa, Idaho

Nampa's water systems logged 21 health-based EPA violations in 2021–2026, most recently in 2025 — most often arsenic. Health-based violations mean a federal limit or treatment standard was exceeded; check the systems below and your utility's annual report for specifics.

C-Fair
Nampa water grade: C-
Fair — our A–F grade from this city's EPA compliance record, relative to Idaho and the nation. How we grade →
Health-based violations, 2021–202621
Arsenic12
Lead And Copper Rule Revisions3
Groundwater Rule3
Gross Alpha, Excl. Radon And U2
Nampa City Of100,200 served
Shalimar Subd370 served
Belle Aire Acres 2350 served
Evergreen Mobile Park284 served
Idaho quality rank#32 / 51 (81.7/100)
Idaho avg hardness100 PPM (moderately hard)
Want to know what's actually in your Nampa water?

Averages describe states, not your faucet. A certified home water test screens for lead, nitrates, bacteria and dozens of other contaminants — the same categories EPA regulates.

Test your water at home

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Nampa tap water FAQ

Is tap water safe to drink in Nampa?

Nampa's systems logged 21 health-based violations in 2021–2026, most commonly arsenic. A violation is a red flag for a period of time, not a permanent condition — your utility's current Consumer Confidence Report shows today's status, and a certified home test shows what's at your tap.

Who supplies Nampa's water?

Nampa City Of (serving about 100,200 people); Shalimar Subd (serving about 370 people); Belle Aire Acres 2 (serving about 350 people); Evergreen Mobile Park (serving about 284 people). Data: EPA Safe Drinking Water Information System, July 2026.

How hard is the water in Nampa?

City-level hardness isn't published in a single federal dataset, but Idaho averages 100 PPM — "moderately hard" on the USGS scale. Your utility's water quality report lists Nampa's exact hardness, or a $10 test strip tells you in a minute. If it comes back over 120 PPM, see our water softener guidance in the purification calculator.

Do I need a water filter in Nampa?

With 21 health-based violations on record in 2021–2026, a certified filter is reasonable insurance here: reverse osmosis ($150–$1,300 installed, Angi 2026) covers lead, nitrates and PFAS at the tap. Test first ($50–$200) so you buy for what's actually present.

Want to know what's actually in your Nampa water?

Averages describe states, not your faucet. A certified home water test screens for lead, nitrates, bacteria and dozens of other contaminants — the same categories EPA regulates.

Test your water at home

We may earn a commission if you request quotes through this link. It costs you nothing and never affects the data we publish.