Is Rainbow Lake Tap Water Safe? Quality Report

Water source: Ground water
Ownership: Local government
Counties served: Mason

Compliance record

Formal violations the EPA has on file for this supplier. A health-based violation means a contaminant limit or a required treatment was breached; the rest are monitoring or reporting failures — still violations, but not a measured health risk.

health-based violations

violations on file

still open

Violation	Type	Status	Period
MON	Monitoring	Resolved	2018-09-01 → 2018-09-30
MR	Monitoring	Archived	2006-11-01 → 2006-11-30
Other	Monitoring	Resolved	1999-10-19 → 1999-12-31
MR	Monitoring	Resolved	1997-07-01 → 1998-01-01
MR	Monitoring	Archived	1991-12-01 → 1991-12-31
MR	Monitoring	Archived	1979-10-01 → 1979-10-31
MR	Monitoring	Archived	1979-10-01 → 1979-10-31
MR	Monitoring	Archived	1979-10-01 → 1979-10-31
MR	Monitoring	Archived	1979-10-01 → 1979-10-31
MR	Monitoring	Archived	1979-10-01 → 1979-10-31

Other contaminants detected

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 this system's samples — over 100% is worth reading, but is not by itself a violation. Where a single sample came in higher than that percentile, it is noted under the bar. Formal violations are listed separately.

Contaminant	Level vs EPA limit	Detection rate	Source	Period
Nitrate	500 µg/L 5% of the EPA limit 10000 µg/L	10/10	SYR4	2013–2017
Lead	0.0050 mg/L 33% of the EPA limit 0.0150 mg/L	9/9	LCR	2025
Chloroform	0.3000 µg/L No EPA limit set	1/4	SYR4	2012–2017
Nitrate-Nitrite	500 µg/L 5% of the EPA limit 10000 µg/L	1/1	SYR4	2013
TTHM	0.3000 µg/L 0.4% of the EPA limit 80 µg/L	1/1	SYR4	2017

50 contaminants tested, none detected

1,1,1-Trichloroethane1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-Dichloroethane1,2-Dichloropropane2,4,5-TP2,4-DAntimony, TotalArsenicBariumBenzeneBeryllium, TotalBromodichloromethaneBromoformChlorobenzeneCopperCyanideCadmiumCarbon TetrachlorideChromiumDichloromethaneDalaponDibromoacetic AcidDibromochloromethaneDichloroacetic AcidDinosebEthylbenzeneFluorideLeadMercuryMonobromoacetic AcidMonochloroacetic AcidNitritePentachlorophenolPicloramSeleniumStyreneTetrachloroethyleneThallium, TotalTolueneTotal Haloacetic Acids (HAA5)Trichloroacetic AcidTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

Utility contact

Contact: Brandy Milroy

Frequently asked questions about Rainbow Lake

Is Rainbow Lake tap water safe to drink?

EPA monitoring detected 5 contaminants in Rainbow Lake's water. A detection isn't the same as a violation — most levels are within federal limits. See each level and source above, and the utility's annual Consumer Confidence Report for its official compliance status.

What contaminants were detected in Rainbow Lake's water?

EPA monitoring detected Nitrate, Lead, Chloroform, Nitrate-Nitrite, TTHM. The full list with the level and data source for each is above.

How many people does Rainbow Lake serve?

Rainbow Lake reports serving 168 people in Washington, per its EPA record.

Has Rainbow Lake had any water quality violations?

The EPA has 14 violations on file for Rainbow Lake, of which 0 are health-based (a contaminant limit or required treatment was breached) and 0 remain open. The rest are monitoring or reporting failures.

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.