States → Idaho
State profile · EPA SDWIS + UCMR5
Idaho Drinking Water Quality
2,005 public water systems serve 1,743,912 people across Idaho, with every Safe Drinking Water Act violation and UCMR5 PFAS result on record.
- 2,005
- Water systems
- 104,850
- Total violations
- 96.1%
- Systems w/ a violation
- 66.7%
- PFAS detection rate
The verdict
Across Idaho, 1,927 of 2,005 water systems (96.1%) carry at least one EPA violation, and 40 of 60 UCMR5-tested systems show PFAS.
- 104,850
- Total EPA violations on record
- 19%
- Health-based (MCL / treatment)
- 96.1%
- Systems with ≥1 violation
- 66.7%
- UCMR5 PFAS detection rate
Water Systems
2,005
Total Violations
104,850
Violation Rate
96.1%
PFAS Detection
66.7%
40 of 60 tested
Violation Composition
How Idaho's 104,850 violations break down by type, per EPA SDWIS classification.
Health-based (19,965) Monitoring/Reporting (84,885)
| Metric | Value | Share |
|---|---|---|
| Public water systems | 2,005 | - |
| Population served | 1,743,912 | - |
| Total violations | 104,850 | 100% |
| Health-based violations | 19,965 | 19.0% |
| Systems with violations | 1,927 | 96.1% |
| PFAS detection rate | 40 of 60 | 66.7% |
Health-based violations indicate the contaminant exceeded an EPA Maximum Contaminant Level (MCL) or treatment-technique requirement. Monitoring/reporting violations indicate procedural issues (missed tests, late reports) - not necessarily a contamination event.
Largest Water Systems
Veolia Water Idaho
Boise, ID · 264,978 served
Meridian Water Dept
Meridian, ID · 147,340 served
Nampa City Of
Nampa, ID · 100,200 served
Caldwell City Of
Caldwell, ID · 74,000 served
Idaho Falls City Of
Idaho Falls, ID · 69,450 served
Pocatello City Of
Pocatello, ID · 58,231 served
Twin Falls City Of
Twin Falls, ID · 56,121 served
Coeur D Alene City Of
Coeur D Alene, ID · 54,115 served
Rexburg City Of
Rexburg, ID · 40,462 served
Kuna City Of
Kuna, ID · 32,038 served
Moscow Water Dept
Moscow, ID · 26,000 served
Falls Water Company Inc
Idaho Falls, ID · 22,650 served
Post Falls City Of
Post Falls, ID · 20,285 served
Lewiston Orchards Irrigation Dist
Lewiston, ID · 20,000 served
Ammon City Of
Ammon, ID · 17,338 served
Chubbuck City Of
Chubbuck, ID · 15,842 served
Lewiston City Of
Lewiston, ID · 15,001 served
Mountain Home, City Of
Mountain Home, ID · 14,651 served
Star Sewer and Water Dist Water System
Star, ID · 14,000 served
Middleton City Of
Middleton, ID · 13,190 served
Most Violations
#1 Valley View Subdivision Rexburg
1,278 #2 Clearwater Water Dist Clearwater
1,066 #3 Pocatello City Of Pocatello
961 #4 Aspen Ridge Subd Rexburg
868 #5 Symms Fruit Ranch Inc Caldwell
682 #6 Mission Creek Water Assn Bonners Ferry
674 #7 Post Falls City Of Post Falls
658 #8 The Learning Academy Driggs
605 #9 Mountain Home Air Force Base Mountain Home Afb
574 #10 Kuna City Of Kuna
554 #11 Smiley Creek Water Users Assn Inc Ketchum
553 #12 Red Rock Water LLC Lewiston
521 #13 Caldwell City Of Caldwell
518 #14 Partners Produce Payette
515 #15 Shotgun Cherokee Subd 5 Rexburg
465 Counties in Idaho
Ada
87 systems · 511,181 served
· 5,380 violations
Canyon
143 systems · 214,619 served
· 9,692 violations
Kootenai
195 systems · 178,648 served
· 7,546 violations
Bonneville
135 systems · 138,969 served
· 4,633 violations
Bannock
49 systems · 83,349 served
· 2,778 violations
Twin Falls
54 systems · 76,016 served
· 2,851 violations
Madison
33 systems · 50,343 served
· 998 violations
Latah
35 systems · 41,303 served
· 2,229 violations
Nez Perce
25 systems · 39,929 served
· 1,887 violations
Bonner
152 systems · 39,891 served
· 5,382 violations
Bingham
74 systems · 36,624 served
· 3,178 violations
Elmore
45 systems · 26,866 served
· 3,868 violations
Blaine
46 systems · 23,812 served
· 2,888 violations
Payette
20 systems · 19,821 served
· 2,033 violations
Jefferson
63 systems · 19,584 served
· 2,465 violations
Cassia
50 systems · 19,063 served
· 3,276 violations
Jerome
24 systems · 17,778 served
· 1,336 violations
Shoshone
37 systems · 15,611 served
· 1,510 violations
Minidoka
28 systems · 15,130 served
· 2,351 violations
Fremont
91 systems · 14,857 served
· 6,494 violations
Valley
57 systems · 12,433 served
· 1,987 violations
Boundary
20 systems · 11,485 served
· 1,933 violations
Franklin
22 systems · 11,019 served
· 2,401 violations
Idaho
58 systems · 10,236 served
· 3,546 violations
Gem
34 systems · 9,813 served
· 1,883 violations
Gooding
26 systems · 9,512 served
· 1,336 violations
Bear Lake
33 systems · 7,887 served
· 1,296 violations
Teton
26 systems · 7,429 served
· 1,597 violations
Boise
56 systems · 7,343 served
· 3,508 violations
Benewah
15 systems · 7,006 served
· 998 violations
Showing top 30 of 44 counties.
Drinking Water Guides
Frequently Asked Questions
How many water systems are in Idaho? ▼
Idaho has 2,005 public water systems serving approximately 1,743,912 people. These include community water systems, non-transient non-community systems, and transient non-community systems regulated under the Safe Drinking Water Act.
How many drinking water violations are in Idaho? ▼
Idaho has 104,850 total drinking water violations on record, with 19,965 classified as health-based violations. 96.1% of water systems in the state have at least one violation.
Has PFAS been found in Idaho drinking water? ▼
Of 60 water systems tested for PFAS in Idaho, 40 had PFAS detected, a 66.7% detection rate. PFAS are persistent "forever chemicals" that do not break down in the environment.
What is the violation rate for Idaho water systems? ▼
Idaho's violation rate is 96.1%. This measures the percentage of public water systems that have at least one recorded violation in the EPA SDWIS database, including both health-based and monitoring/reporting violations.
Where does this Idaho water data come from? ▼
All drinking water data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS is the federal database that tracks compliance for all public water systems regulated under the Safe Drinking Water Act.
Data Sources & Methodology
Drinking water violation data from the EPA Safe Drinking Water Information System (SDWIS). PFAS testing data from the UCMR5 monitoring program. SDWIS tracks all public water systems regulated under the Safe Drinking Water Act.
Read our methodology - how this data is sourced, computed, and verified.
Related
Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial
Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.