Is Preston, ID Tap Water Safe? Quality & Contaminants

What was found in Preston's water

The level at the city's main supplier, the highest level anywhere in the city, the EPA limit for each, and where every figure comes from.

Contaminant	Level vs EPA limit	Suppliers	Source
Nitrate	220 µg/L 2.2% of the EPA limit 10000 µg/L Main supplier: PRESTON CITY OF · 5,591 people · 2019 Highest in the city: 11003.5 µg/L — WHITNEY NASHVILLE WATER WORKS · 403 people · 2019	6/9	SYR4
Nitrate-Nitrite	7030 µg/L 70% of the EPA limit 10000 µg/L Highest in the city: BANIDA WATER AND SEWER DIST · 180 people · 2017	2/9	SYR4
Fluoride	600 µg/L 15% of the EPA limit 4000 µg/L Highest in the city: WHITNEY NASHVILLE WATER WORKS · 403 people · 2019	3/9	SYR4
Barium	11 µg/L 0.5% of the EPA limit 2000 µg/L Main supplier: PRESTON CITY OF · 5,591 people · 2019 Highest in the city: 89.5 µg/L — BANIDA WATER AND SEWER DIST · 180 people · 2019	8/9	SYR4
TTHM	3.512 µg/L 4.4% of the EPA limit 80 µg/L Main supplier: PRESTON CITY OF · 5,591 people · 2019 Highest in the city: 8.051 µg/L — PRESTON EASTSIDE WATER CO · 120 people · 2019	8/9	SYR4
Selenium	7.95 µg/L 16% of the EPA limit 50 µg/L Highest in the city: WHITNEY NASHVILLE WATER WORKS · 403 people · 2019	5/9	SYR4
Arsenic	1 µg/L 10% of the EPA limit 10 µg/L Main supplier: PRESTON CITY OF · 5,591 people · 2019 Highest in the city: 7.65 µg/L — WHITNEY NASHVILLE WATER WORKS · 403 people · 2019	4/9	SYR4
Total Haloacetic Acids (HAA5)	4.8345 µg/L 8.1% of the EPA limit 60 µg/L Highest in the city: FAIRVIEW WATER DIST · 1,300 people · 2019	6/9	SYR4
Combined Uranium	0.1300 µg/L 0.4% of the EPA limit 30 µg/L Main supplier: PRESTON CITY OF · 5,591 people · 2016 Highest in the city: 4.417 µg/L — BANIDA WATER AND SEWER DIST · 180 people · 2019	8/9	SYR4
Gross Alpha, Excl. Radon And U	4.16 pCi/L 28% of the EPA limit 15 pCi/L Highest in the city: BANIDA WATER AND SEWER DIST · 180 people · 2019	5/9	SYR4
Copper	4 µg/L 0.3% of the EPA limit 1300 µg/L Highest in the city: FAIRVIEW WATER DIST · 1,300 people · 2017	1/9	SYR4
Chromium	2.95 µg/L 3% of the EPA limit 100 µg/L Highest in the city: BANIDA WATER AND SEWER DIST · 180 people · 2019	4/9	SYR4
Bromoform	2.33 µg/L No EPA limit set Highest in the city: BANIDA WATER AND SEWER DIST · 180 people · 2013	1/9	SYR4
Combined Radium (-226 And -228)	0.1030 pCi/L 2.1% of the EPA limit 5 pCi/L Main supplier: PRESTON CITY OF · 5,591 people · 2016 Highest in the city: 1.64105 pCi/L — BANIDA WATER AND SEWER DIST · 180 people · 2017	6/9	SYR4
Dibromochloromethane	1.24 µg/L No EPA limit set Highest in the city: BANIDA WATER AND SEWER DIST · 180 people · 2013	1/9	SYR4
Chloroform	0.6700 µg/L No EPA limit set Main supplier: PRESTON CITY OF · 5,591 people · 2016	1/9	SYR4
Lead	0.0030 mg/L 20% of the EPA limit 0.0150 mg/L Main supplier: PRESTON CITY OF · 5,591 people · 2022 Highest in the city: 0.0070 mg/L — CUB RIVER ACRES · 180 people · 2025	8/9	LCR

Each bar shows the measured level as a share of the EPA limit: green is well under, amber is close to it, red is over. For lead and copper the limit applies to exactly the 90th-percentile figure shown, so red there means a real exceedance. For everything else the limit applies to a running annual average while the figure is the 95th percentile of the system's samples — over 100% is worth reading, but is not by itself a violation. Formal violations are listed separately. These are the utilities' own EPA-reported results, not a city-wide average. A detection means the lab measured the substance — it isn't the same as exceeding a legal limit. Hover a source tag to see the EPA program and years behind each figure.

Water suppliers serving Preston

Supplier	Population served
PRESTON CITY OF	5,591
FAIRVIEW WATER DIST	1,300
WHITNEY NASHVILLE WATER WORKS	403
CUB RIVER ACRES	180
BANIDA WATER AND SEWER DIST	180
PRESTON EASTSIDE WATER CO	120
BIRCH CREEK CULINARY	120
STRAWBERRY MINK CREEK WATER ASSN	75
WINDER WATER SYSTEM	20

Frequently asked questions about Preston tap water

Is Preston tap water safe to drink?

EPA testing detected 17 contaminants in the water serving Preston. A detection isn't the same as a violation — most detected levels are within federal limits. Check the level and source for each contaminant above, and your utility's annual Consumer Confidence Report for the official compliance status.

How many water suppliers serve Preston?

9 public water suppliers report drinking-water monitoring for Preston, Idaho to the EPA. Each is listed above with its population served.

What contaminants are in Preston's water?

The contaminants EPA monitoring detected in Preston include Nitrate, Nitrate-Nitrite, Fluoride, Barium, TTHM. The full list, with the level at the main supplier and the data source, is in the table above.

Where does this data come from?

Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.