Is Riddle, OR Tap Water Safe? Quality & Contaminants

What was found in Riddle'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
Copper	365.9 µg/L 28% of the EPA limit 1300 µg/L Main supplier: RIDDLE, CITY OF · 1,224 people · 2019 Highest in the city: 538 µg/L — LAWSON ACRES WATER ASSOCIATION · 75 people · 2019	4/5	SYR4
Nitrate	190 µg/L 1.9% of the EPA limit 10000 µg/L Main supplier: RIDDLE, CITY OF · 1,224 people · 2019	1/5	SYR4
Total Haloacetic Acids (HAA5)	46.56 µg/L 78% of the EPA limit 60 µg/L Main supplier: RIDDLE, CITY OF · 1,224 people · 2019 Highest in the city: 165.45 µg/L — LAWSON ACRES WATER ASSOCIATION · 75 people · 2019	3/5	SYR4
TTHM	63.695 µg/L 80% of the EPA limit 80 µg/L Main supplier: RIDDLE, CITY OF · 1,224 people · 2019 Highest in the city: 111.2 µg/L — LAWSON ACRES WATER ASSOCIATION · 75 people · 2019	3/5	SYR4
Lead	18.5 µg/L 123% of the EPA limit, at the 95th percentile of samples — 15 µg/L Main supplier: RIDDLE, CITY OF · 1,224 people · 2019 Highest in the city: 71.2 µg/L — SOUTH UMPQUA WATER ASSOCIATION · 575 people · 2017	4/5	SYR4
Combined Radium (-226 And -228)	0.0900 pCi/L 1.8% of the EPA limit 5 pCi/L Main supplier: RIDDLE, CITY OF · 1,224 people · 2019	1/5	SYR4
Lead	0.0100 mg/L 67% of the EPA limit 0.0150 mg/L Main supplier: RIDDLE, CITY OF · 1,224 people · 2025	5/5	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 Riddle

Supplier	Population served
RIDDLE, CITY OF	1,224
SOUTH UMPQUA WATER ASSOCIATION	575
DIAMOND LAKE LODGE/RESORT	90
LAWSON ACRES WATER ASSOCIATION	75
WINCHESTER RIDGE	50

Frequently asked questions about Riddle tap water

Is Riddle tap water safe to drink?

EPA testing detected 7 contaminants in the water serving Riddle. 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 Riddle?

5 public water suppliers report drinking-water monitoring for Riddle, Oregon to the EPA. Each is listed above with its population served.

What contaminants are in Riddle's water?

The contaminants EPA monitoring detected in Riddle include Copper, Nitrate, Total Haloacetic Acids (HAA5), TTHM, Lead. 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.