Is Tonasket, WA Tap Water Safe to Drink?
Graded D — but Copper was detected above EPA limits. Here's what's in the water and how to remove it. What to do next ↓
48/100
waterverge.com Tonasket, WA — Water Quality Report
Tonasket's drinking water received a grade of D (48 out of 100), indicating poor water quality. The city's 35 water systems serve approximately 7,047 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 1524 violations on record, including 134 health-based violations. 64 remain unresolved.
What to know about Tonasket's water
Tonasket ranks #225 out of 294 cities in Washington for water quality, placing it among the lowest-rated in the state.
Tonasket 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.
The system has seen 109 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Tonasket, WA water safe to drink?
Tonasket's drinking water has significant quality concerns based on EPA testing data. With a grade of D (48/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 35 water systems serve approximately 7,047 residents using groundwater (wells).
Recent water quality updates for Tonasket
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Tonasket's water quality assessment. Grade: D (48/100).
Contaminants: Revised Total Coliform Rule.
Contaminants: Revised Total Coliform Rule.
1 health-based. Contaminants: Nitrate, Revised Total Coliform Rule, Hexachlorocyclopentadiene.
Federal disaster declaration (FEMA DR-4650). Flood event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-3227). Coastal Storm event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Tonasket's water supply.
Well within EPA limits.
Exceeds EPA action level. Copper can leach from household plumbing — flush taps for 30 seconds before drinking.
Violation history
Tonasket's water system has 1,524 total violations on record, including 134 health-based violations. 64 remain unresolved. 109 violations were issued in the last 5 years.
Flood & environmental risk
Okanogan County has experienced 4 federally declared disasters since 1972. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies. Local water sources include Antoine Creek, Bonaparte Creek, Okanogan River.
Where does Tonasket's water come from?
Tonasket's drinking water comes from groundwater (wells), supplied by 35 water systems serving approximately 7,047 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Antoine Creek (river), Bonaparte Creek (river), Okanogan River (river).
What Tonasket residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Tonasket's water.
Your water utility is required to publish an annual Consumer Confidence Report (CCR) with detailed testing results. Ask for the latest copy or check your utility's website.
Tonasket's area has a history of flooding. After severe weather, watch for boil water advisories from your local utility.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Violation summary
Violations & advisories
Drought conditions
D1 — moderate droughtOkanogan County is currently in D1 (moderate drought) per the U.S. Drought Monitor (week of May 5, 2026). Drought can elevate disinfection-byproduct (TTHM/HAA5) levels and taste/odor issues as utilities draw from lower reservoirs.
Source: U.S. Drought Monitor, updated weekly by NDMC, USDA, and NOAA.
Flood & disaster history
Okanogan County has experienced 4 federally declared disasters since 1972. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Recommended water filters
Based on contaminants detected in Tonasket's water supply, we recommend the following filter types.
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 |
| Copper (90th percentile) CopperInorganic A metal that enters drinking water mainly through corrosion of copper plumbing. Small amounts are essential for health, but excess levels are harmful. Health EffectsGastrointestinal distress (nausea, vomiting, diarrhea) at short-term high levels; liver and kidney damage from long-term exposure. EPA Limit1.3 mg/L action level Common SourcesCorrosion of copper household plumbing, erosion of natural deposits. | 1.38 | 1.3 | mg/L | Inorganic | Over Limit |
Lead level trend (90th percentile)
Copper level trend (90th percentile)
See how Tonasket compares by contaminant
Explore where Tonasket ranks among all Washington cities for specific contaminants.
Water source & infrastructure
Where Tonasket's water comes from
Tonasket's drinking water is drawn from underground aquifers through wells.
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 7,047 people through 35 water systems.
Water bodies near Tonasket
Tonasket is located near 3 notable water bodies. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Tonasket
| System Name | PWSID | Population | Source |
|---|---|---|---|
| TONASKET WATER SYSTEM | WA5388700 | 2,392 | GW |
| INCHELIUM WATER DISTRICT | WA5335550 | 540 | GW |
| CORRAL SPRINGS WATER SYSTEM | WA5351714 | 336 | GW |
| PROGRESSIVE FLAT WATER ASSN | WA5369650 | 335 | GWP |
| Crane Ranch | WA5315818 | 329 | GW |
| SANDFLAT WATER ASSOCIATION | WA5309064 | 260 | GW |
| SUNCREST PLAT WATER SYSTEM | WA5385207 | 260 | GW |
| COLEMAN BUTTE WATER ASSN | WA5313940 | 250 | GW |
| LOOMIS WATER USERS ASSN INC | WA5348200 | 225 | GW |
| HANSON HARBOR HOMEOWNERS ASSN | WA5319928 | 220 | GW |
| AFC RANCH 1 | WA5303427 | 217 | GW |
| RIVER ROAD MOBILE HOME PARK | WA5317631 | 150 | GW |
| ASTON ESTATES | WA5309066 | 141 | GW |
| AFC RANCH 2 | WA5300863 | 125 | GW |
| CRUMBACHER ESTATES WATER SYSTEM | WA5313916 | 111 | GW |
| MARTIN CREEK COMMUNITY ASSN | WA5351877 | 108 | GW |
| HOMESTEAD MOBILE HOME PARK | WA5301576 | 105 | GW |
| PINE FOREST WATER SYSTEM | WA5367393 | 90 | GW |
| OLD ORCHARD ESTATES WATER SYSTEM | WA5307748 | 86 | GW |
| LOST RIVER AIRPORT ASSOCIATION | WA5348348 | 72 | GW |
| WOLF CREEK PROPERTY OWNERS ASSN | WA5311476 | 71 | GW |
| PINECREST SUBDIVISON OWNERS | WA5313909 | 63 | GW |
| CASCADE FOOTHILLS | WA5307285 | 61 | GW |
| VISTA VUE WATER USERS ASSN | WA5320226 | 60 | GW |
| WITHROW WATER WORKS | WA5398000 | 60 | GW |
| APPLEWAY TRAILER COURT | WA5300603 | 54 | GW |
| COLUMBIA SPRINGS ESTATES | WA5304298 | 54 | GW |
| JOHNSON CREEK WATER USERS ASSN | WA5339411 | 48 | GW |
| Robison Tract / Teeny | WA5367605 | 46 | GW |
| RIVERWOOD WATER SYSTEM | WA5373032 | 43 | GW |
| ELM TREE WATER & SEWER ASSN | WA5323128 | 38 | GW |
| MANY LAKES MOBILE HOME PARK | WA5304670 | 37 | GW |
| Valley View Estates Water System | WA5306321 | 28 | GW |
| TWIN PINES MOBILE HOME PARK | WA5331790 | 25 | GW |
| AZWELL ORCHARDS | WA5303523 | 7 | GW |
How Tonasket compares
Full Washington rankings →Tonasket's score of 48/100 is on par with the average of 53/100 among major Washington cities. It outscores 6 of 10 nearby cities.
Nearby cities
View Washington rankings →About Tonasket, WA
Wikipedia →Tonasket is a city in Okanogan County, Washington, United States. The population was 1,103 at the 2020 census.
Learn more about your water
Guides and resources related to Tonasket's water quality findings.
Explore water quality across Okanogan
Frequently asked questions
Is Tonasket, WA tap water safe to drink?
Tonasket's water quality earned a grade of D (48/100). Significant issues have been found. A water filter is strongly recommended. The city ranks #225 out of 294 cities tested in Washington.
What contaminants are in Tonasket's water?
Lead was measured at 0.0 ppb (90th percentile). 1524 violations are on record.
How is Tonasket'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 Tonasket?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Tonasket's water come from?
Tonasket's water is sourced from Groundwater. The city has 35 water systems serving approximately 7,047 residents.
What health violations has Tonasket's water system had?
Tonasket has 134 health-based violations on record. The most recent violation was recorded in December 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 64 violations remain unresolved.
Is Tonasket's groundwater at risk of contamination?
Tonasket 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 1524 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 Tonasket's water compare to other cities?
Tonasket ranks #225 out of 294 cities in Washington (better than 23% of state cities) and #13508 out of 15744 cities nationally (14th percentile). The grade of D reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.