Is Winlock, WA Tap Water Safe to Drink?
Graded B+, with 6 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
83.2/100
waterverge.com Winlock, WA — Water Quality Report
Winlock's drinking water received a grade of B+ (83.2 out of 100), indicating good water quality. The city's 2 water systems serve approximately 3,567 residents using groundwater.
Lead levels were measured at 2.0 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 241 violations on record, including 4 health-based violations. 6 remain unresolved.
What to know about Winlock's water
Winlock ranks #117 out of 294 cities in Washington for water quality, placing it mid-range in the state.
Winlock 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.
Water quality score
See methodology →Is Winlock, WA water safe to drink?
Winlock's drinking water has significant quality concerns based on EPA testing data. With a grade of B+ (83.2/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 2 water systems serve approximately 3,567 residents using groundwater (wells).
Recent water quality updates for Winlock
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Winlock's water quality assessment. Grade: B+ (83.2/100).
Federal disaster declaration (FEMA DR-3629). Flood event — may have impacted local water infrastructure.
Contaminants: Revised Total Coliform Rule.
Federal disaster declaration (FEMA DR-4650). Flood event — may have impacted local water infrastructure.
Contaminants: Consumer Confidence Rule.
Contaminants: Consumer Confidence Rule.
Key contaminant findings
Based on the most recent EPA sampling data for Winlock's water supply.
Well within EPA limits.
Violation history
Winlock's water system has 241 total violations on record, including 4 health-based violations. 6 remain unresolved. 1 violation was issued in the last 5 years.
Flood & environmental risk
Lewis County has experienced 10 federally declared disasters since 1991. 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 South Fork Chehalis River, Newaukum River.
Where does Winlock's water come from?
Winlock's drinking water comes from groundwater (wells), supplied by 2 water systems serving approximately 3,567 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include South Fork Chehalis River (river), Newaukum River (river).
What Winlock residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Winlock'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.
Winlock'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
Top industrial polluters within 10 miles of Winlock
Industrial polluters nearby
Reported releases to surface water by facilities near Winlock, ranked by pounds discharged annually.
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
ALADDIN MANUFACTURING CARPET CUSHION - CHEHALIS WA CHEHALIS, WA98532 | — | — | 9.9 mi |
IMPERIAL GROUP MANUFACTURING CHEHALIS, WA98532 | — | — | 9.4 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Superfund sites within 10 miles of Winlock
Superfund sites nearby
Federally tracked hazardous-waste sites on the EPA National Priorities List. Proximity does not necessarily indicate tap-water contamination — the connection depends on hydrology and treatment.
- HAMILTON LABREE ROADS GW CONTAMINATION9.2 mi
Source: EPA Superfund National Priorities List
Flood & disaster history
Lewis County has experienced 10 federally declared disasters since 1991. 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. | 2.0 | 15 | ppb | Inorganic | Safe |
Lead level trend (90th percentile)
See how Winlock compares by contaminant
Explore where Winlock ranks among all Washington cities for specific contaminants.
Water source & infrastructure
Where Winlock's water comes from
Winlock'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 3,567 people through 2 water systems.
Water bodies near Winlock
Winlock is located near 2 notable water bodies. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Winlock
| System Name | PWSID | Population | Source |
|---|---|---|---|
| WINLOCK CITY OF | WA5397500 | 3,502 | GW |
| FROST ROAD PARK | WA5326647 | 65 | GW |
How Winlock compares
Full Washington rankings →Winlock's score of 83.2/100 is above the average of 53/100 among major Washington cities. It outscores 9 of 10 nearby cities.
Nearby cities
View Washington rankings →About Winlock, WA
Wikipedia →Winlock is a city in Lewis County, Washington, United States. The population was 1,472 at the 2020 census, and was estimated to be 2,515 in 2024. It was named after territorial army general, William Winlock Miller, who briefly resided there. Winlock is mostly famous for having the World's Largest Egg, reflecting its former status as a major producer of eggs. Early in its history, Winlock attracted many immigrants from Finland, Germany, and Sweden.
Learn more about your water
Guides and resources related to Winlock's water quality findings.
Explore water quality across Lewis
Frequently asked questions
Is Winlock, WA tap water safe to drink?
Winlock's water quality earned a grade of B+ (83.2/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #117 out of 294 cities tested in Washington.
What contaminants are in Winlock's water?
Lead was measured at 2.0 ppb (90th percentile). 241 violations are on record.
How is Winlock'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 Winlock?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Winlock's water come from?
Winlock's water is sourced from Groundwater. The city has 2 water systems serving approximately 3,567 residents.
What health violations has Winlock's water system had?
Winlock has 4 health-based violations on record. The most recent violation was recorded in October 2023. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 6 violations remain unresolved.
Is Winlock's groundwater at risk of contamination?
Winlock 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 241 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 Winlock's water compare to other cities?
Winlock ranks #117 out of 294 cities in Washington (better than 60% of state cities) and #6545 out of 15744 cities nationally (58th percentile). The grade of B+ reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.