01The verdict: is Coulee City water safe?
Coulee City's tap water meets most EPA standards but has areas that warrant attention. With a grade of A (90.4/100), some contaminant levels or compliance issues suggest that residents may benefit from additional filtration. The city's 1 water system serves approximately 944 residents using groundwater (wells).
2 unresolved violations on record
EPA records show open compliance items for this system. Most are administrative, but unresolved items are worth watching.
See what was cited ↓Lead is well under the limit
90th-percentile lead is 0.0 ppb — beneath the 15 ppb federal action level and under the 5 ppb watch threshold.
See the trend ↓6 violations in the last five years
Recent compliance history is the best predictor of future problems — the year-by-year record is below.
See the record ↓Coulee City's drinking water received a grade of A (90.4 out of 100), indicating excellent water quality. The city's 1 water system serves approximately 944 residents using groundwater.
Lead levels were measured at 0.0 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program. The system has 20 violations on record, including 6 health-based violations. 2 remain unresolved.
Coulee City ranks #39 out of 294 cities in Washington for water quality, placing it above average in the state. Coulee City relies on groundwater, which is generally less vulnerable to surface contamination but can be affected by naturally occurring minerals like arsenic and nitrate, as well as agricultural and industrial runoff. As a small community water system, Coulee City may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities. The system has seen 6 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
02What's in Coulee City's water
Every contaminant flagged in Coulee City, on one shared scale: distance to its own legal limit. The red line is the limit — anything past it is out of compliance, and the closer a bar gets, the less headroom the system has.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 0.0 | 15 | ppb | Inorganic | Safe |
Cities ranked by 90th-percentile lead PF PFAS in Washington
Cities ranked by compounds detected Cu Copper in Washington
Cities ranked by 90th-percentile copper
03Coulee City's ten-year track record
Each box is one year. A green check means no EPA violations; a numbered badge counts that year's violations — red if any were health-based, amber if they were monitoring or paperwork issues. The system has 20 violations on record, including 6 health-based violations. 2 remain unresolved.
8 of the last ten years were clean. The numbered years had EPA violations — red when any were health-based, amber when they were paperwork or missed-testing issues.
▼ Down 2 ppb since 1993. Latest reading: 0 ppb (2024) — 0% of the action level. Sampled at higher-risk homes (90th percentile).
04Where Coulee City's water comes from
Coulee City's drinking water is drawn from underground aquifers through wells.
Groundwater
Underground aquifers reached by wells — naturally filtered, but can carry minerals like arsenic and nitrate.
Local treatment
Groundwater generally needs less treatment — typically disinfection and, where needed, mineral removal.
1 system
1 water system, operated under local government ownership.
944 people
Residents served across Coulee City's service area.
Groundwater is naturally filtered through rock and soil layers, generally requiring less treatment than surface water. However, it can contain naturally occurring contaminants like arsenic, radon, and minerals. Agricultural activity, septic systems, and industrial operations near well fields can introduce nitrates, pesticides, and volatile organic compounds. The system is operated by local government ownership and serves approximately 944 people through 1 water system.
| System name | PWSID | Population | Source |
|---|---|---|---|
| COULEE CITY TOWN OF | WA5315300 | 944 | Groundwater |
05Pressure on Coulee City's watershed
Outside forces that shape what reaches the treatment plant. None of these is a verdict on the tap by itself — but each adds pressure worth knowing about.
Flood & storm history
2 federal disaster declarations on record for Grant County. Flooding and severe storms can overwhelm treatment plants, cause sewage overflows, and push runoff into supplies.
Drought
Grant County is in D1 (moderate drought) per the U.S. Drought Monitor (week of Jul 2026). Drought can raise disinfection-byproduct levels and taste/odor issues as utilities draw from lower reservoirs.
06How Coulee City compares
Scores for nearby Washington cities on one line, with the average marked.
dashed line = Washington average (53/100)
Coulee City scores 90.4/100 — above the Washington average of 53/100. It outscores 9 of 10 nearby cities. Full Washington rankings →
42.3 / 100FTacoma, WA
32.2 / 100FVancouver, WA
32.9 / 100FSpokane, WA
39.2 / 100FKent, WA
44.4 / 100ABellevue, WA
91.6 / 100
Compare all cities in the county — grades, violations, and contaminant data side by side.→
07What to do at home
Steps matched to what testing actually found in Coulee City's water — not generic advice.
A basic carbon filter still helps
Coulee City's water meets federal standards, but a simple carbon filter improves taste and adds a margin of safety against short-term issues.
Compare tested filters →Read your utility's annual report
Every utility must publish a yearly Consumer Confidence Report with its own testing results. It pairs well with the independent data on this page.
How to read a CCR →Watch for Coulee City alerts
We refresh EPA data monthly and surface new violations, advisories, and boil-water notices for your county on this page.
All water alerts →Frequently asked questions
Is Coulee City, WA tap water safe to drink?
Coulee City's water quality earned a grade of A (90.4/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #39 out of 294 cities tested in Washington.
What contaminants are in Coulee City's water?
Lead was measured at 0.0 ppb (90th percentile). 20 violations are on record.
How is Coulee City's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Coulee City?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Coulee City's water come from?
Coulee City's water is sourced from Groundwater. The city has 1 water system serving approximately 944 residents.
What health violations has Coulee City's water system had?
Coulee City has 6 health-based violations on record. The most recent violation was recorded in January 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 2 violations remain unresolved.
Is Coulee City's groundwater at risk of contamination?
Coulee City uses groundwater, which can be affected by naturally occurring contaminants like arsenic, radon, and nitrate, as well as agricultural runoff and industrial activity. The system has 20 violations on record that may relate to groundwater quality. Groundwater systems are generally less susceptible to surface contamination but should be monitored for emerging contaminants like PFAS.
How does Coulee City's water compare to other cities?
Coulee City ranks #39 out of 294 cities in Washington (better than 87% of state cities) and #2245 out of 15382 cities nationally (85th percentile). The grade of A reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does Coulee City's small water system affect quality?
Coulee City's system serves approximately 944 residents. Small community water systems (under 3,300 people) may have fewer financial resources for infrastructure upgrades and advanced treatment technologies. However, they are held to the same EPA drinking water standards as larger systems. This system has 20 violations on record.