Who supplies Mountain Home’s water
City of Mountain Home Water Division
EPA system ID ID4200032Groundwater from nine wells (#1, 6, 9, 11, 12, 13, 14, 15 and 16).
Mountain Home water report, by the numbers
| What was measured | Result | Federal limit | EWG guideline | Year · source |
|---|---|---|---|---|
| Hardness | 33–55 (average of all wells) mg/L as CaCO3 | No federal limit | — | Undated FAQCity of Mountain Home FAQ |
| Arsenic | 4–7 ppb | 10 ppb | 0.004 ppb | 2022City of Mountain Home 2023 Consumer Confidence Report |
| Nitrate | 0.5–2.3 ppm | 10 ppm | 0.14 ppm | 2023City of Mountain Home 2023 Consumer Confidence Report |
| Uranium | 1–2 µg/L | 30 µg/L | — | 2022City of Mountain Home 2023 Consumer Confidence Report |
| Gross alpha | 5.43 highest pCi/L | 15 pCi/L | — | 2022City of Mountain Home 2023 Consumer Confidence Report |
| TTHMs | 16.8 highest ppb | 80 ppb | 0.15 ppb | 2023City of Mountain Home 2023 Consumer Confidence Report |
| HAA5 | 3.75 highest ppb | 60 ppb | 0.1 ppb | 2023City of Mountain Home 2023 Consumer Confidence Report |
| Di(2-ethylhexyl) phthalate | 1.06 highest µg/L | 6 µg/L | 3 ppb | 2023City of Mountain Home 2023 Consumer Confidence Report |
| Chlorine | 0.278–0.508 ppm | 4 ppm MRDL | — | 2023City of Mountain Home 2023 Consumer Confidence Report |
| Fluoride The city says fluoride is naturally occurring, not added. | 0.49–0.8 ppm | 4 ppm | — | 2022City of Mountain Home 2023 Consumer Confidence Report |
| Copper Lead is not listed in the 2023 report table. | 0.02 highest ppm | 1.3 ppm action level | — | 2022City of Mountain Home 2023 Consumer Confidence Report |
| Chromium-6 (hexavalent) | 2.49 ppb | No federal limit for chromium-6 (total chromium 100 ppb) | 0.02 ppb | 2013–2023 avgEWG Tap Water Database |
EWG figures are utility annual averages for 2021–2023 (radiological 2018–2023) from tests the utilities report to Idaho DEQ. EWG health guidelines are health-based goals, not legal limits. “ND” means not detected.
EPA violations on record (2023–2026)
EPA’s ECHO database lists these for the city system. ECHO’s health flag for the system is “No”, but 12 of the last 12 quarters show some violation:
- Revised Total Coliform Rule treatment-technique violation, August 2025 (resolved December 11, 2025).
- E. coli monitoring and reporting violations in July 2024 and September 2024 (shown as unresolved in ECHO) and June 2026 (resolved June 30, 2026).
- Lead and Copper Rule Revisions reporting and treatment-technique violations, October 2024 (resolved January 2025).
- Synthetic organic chemical monitoring violations, 2023 (resolved December 31, 2025).
The city’s 2023 report also notes two Level 1 coliform assessments (completed March 7 and August 1, 2023) that found no corrective action necessary.
The October 2026 cloudy-water reports
In an October 28, 2026 release, the city said reports of cloudy water were caused by air bubbles from pressure and temperature changes and the drop in irrigation use, and that the water remains safe to drink.
PFAS: the Air Force base vs. city water
Idaho DEQ lists Mountain Home Air Force Base as one of the Department of Defense sites in Idaho with PFAS detections. In September 2016 the base issued a water advisory after a base drinking-water well showed PFOS and PFOA above the EPA health advisory at the time; the well was treated and later results were below the limit. EWG reports a PFHxS average of 3.72 ppt for the base’s own water system (ID4200054).
The base system is separate from City of Mountain Home water. We did not find published PFAS results for the city system itself; ask the city if you want them.
Do you need a softener in Mountain Home?
Probably not for city water. At 33–55 mg/L as CaCO3, Mountain Home city water is soft. If you want to treat it, the more relevant options are carbon filtration for chlorine taste and an under-sink reverse osmosis system for drinking water. Private wells are a different story and should be tested.
On a private well?
Elmore County is served by Central District Health
CDH does not hand out test kits. Its staff collect private-well samples for a fee ($145 collection plus lab fees, July 2026 fee schedule), or you can take a sample to a certified lab yourself. CDH recommends testing well water once a year for bacteria and nitrate.
Treating Mountain Home water
Get an honest recommendation
Tell us what you’re noticing and we’ll recommend only what your water needs, with one written price. If you don’t need a system, we’ll say so.
Frequently asked questions
Is Mountain Home tap water safe to drink?
Why is Mountain Home water cloudy?
Is there PFAS in Mountain Home water?
Is Mountain Home water hard?
Sources
- City of Mountain Home 2023 Consumer Confidence Report
- City of Mountain Home FAQ, water hardness
- City of Mountain Home Water Division
- City of Mountain Home press release on cloudy water (October 28, 2026)
- EPA ECHO violations, City of Mountain Home (ID4200032)
- EWG Tap Water Database, City of Mountain Home (ID4200032)
- EWG Tap Water Database, Mountain Home Air Force Base (ID4200054)
- Idaho DEQ, PFAS and Idaho drinking water (updated September 29, 2026)
- Idaho News, Mountain Home AFB well advisory (September 2016)
- Idaho Capital Sun, Idaho works to find and remove forever chemicals (April 19, 2021)
Honest Water Boise is not affiliated with any utility, Idaho agency or EWG. This guide summarizes public reports for general information and does not replace your utility’s Consumer Confidence Report or a lab test of your own water.
