Is Winthrop, WA Tap Water Safe to Drink?
Graded B, with 9 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
75.6/100
waterverge.com Winthrop, WA — Water Quality Report
Winthrop's drinking water received a grade of B (75.6 out of 100), indicating good water quality. The city's 2 water systems serve approximately 1,445 residents using groundwater.
Lead levels were measured at 1.0 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 84 violations on record, including 57 health-based violations. 9 remain unresolved.
What to know about Winthrop's water
Winthrop ranks #147 out of 294 cities in Washington for water quality, placing it mid-range in the state.
Winthrop 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, Winthrop may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
The system has seen 9 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Winthrop, WA water safe to drink?
Winthrop's drinking water has significant quality concerns based on EPA testing data. With a grade of B (75.6/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 2 water systems serve approximately 1,445 residents using groundwater (wells).
Recent water quality updates for Winthrop
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Winthrop's water quality assessment. Grade: B (75.6/100).
Contaminants: Consumer Confidence Rule.
Contaminants: Revised Total Coliform Rule.
Contaminants: Revised Total Coliform Rule.
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 Winthrop's water supply.
Well within EPA limits.
Violation history
Winthrop's water system has 84 total violations on record, including 57 health-based violations. 9 remain unresolved. 9 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 Chewuch River, Methow River, Twisp River.
Where does Winthrop's water come from?
Winthrop's drinking water comes from groundwater (wells), supplied by 2 water systems serving approximately 1,445 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Chewuch River (river), Methow River (river), Twisp River (river).
What Winthrop residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Winthrop'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.
Winthrop'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.
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. | 1.0 | 15 | ppb | Inorganic | Safe |
Lead level trend (90th percentile)
See how Winthrop compares by contaminant
Explore where Winthrop ranks among all Washington cities for specific contaminants.
Water source & infrastructure
Where Winthrop's water comes from
Winthrop'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 1,445 people through 2 water systems.
Water bodies near Winthrop
Winthrop is located near 3 notable water bodies. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Winthrop
| System Name | PWSID | Population | Source |
|---|---|---|---|
| WINTHROP TOWN OF | WA5397750 | 1,350 | GW |
| EDELWEISS MAINTENANCE COMMISSION | WA5322340 | 95 | GW |
How Winthrop compares
Full Washington rankings →Winthrop's score of 75.6/100 is above the average of 53/100 among major Washington cities. It outscores 9 of 10 nearby cities.
Nearby cities
View Washington rankings →About Winthrop, WA
Learn more about your water
Guides and resources related to Winthrop's water quality findings.
Explore water quality across Okanogan
Frequently asked questions
Is Winthrop, WA tap water safe to drink?
Winthrop's water quality earned a grade of B (75.6/100). Some concerns have been identified. Consider a water filter for an extra layer of protection. The city ranks #147 out of 294 cities tested in Washington.
What contaminants are in Winthrop's water?
Lead was measured at 1.0 ppb (90th percentile). 84 violations are on record.
How is Winthrop'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 Winthrop?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Winthrop's water come from?
Winthrop's water is sourced from Groundwater. The city has 2 water systems serving approximately 1,445 residents.
What health violations has Winthrop's water system had?
Winthrop has 57 health-based violations on record. The most recent violation was recorded in July 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 9 violations remain unresolved.
Is Winthrop's groundwater at risk of contamination?
Winthrop 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 84 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 Winthrop's water compare to other cities?
Winthrop ranks #147 out of 294 cities in Washington (better than 50% of state cities) and #9536 out of 15744 cities nationally (39th percentile). The grade of B reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.