Is Rosalia, WA Tap Water Safe to Drink?
Graded A-, with 10 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
87.3/100
waterverge.com Rosalia, WA — Water Quality Report
Rosalia's drinking water received a grade of A- (87.3 out of 100), indicating good water quality. The city's 2 water systems serve approximately 1,046 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 88 violations on record, including 7 health-based violations. 10 remain unresolved.
What to know about Rosalia's water
Rosalia ranks #77 out of 294 cities in Washington for water quality, placing it mid-range in the state.
Rosalia 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, Rosalia may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Water quality score
See methodology →Is Rosalia, WA water safe to drink?
Rosalia's drinking water has significant quality concerns based on EPA testing data. With a grade of A- (87.3/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 2 water systems serve approximately 1,046 residents using groundwater (wells).
Recent water quality updates for Rosalia
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Rosalia's water quality assessment. Grade: A- (87.3/100).
Contaminants: Nitrate.
Contaminants: Nitrate.
Contaminants: Consumer Confidence Rule.
Federal disaster declaration (FEMA DR-3227). Coastal Storm event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-1100). Flood event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Rosalia's water supply.
Well within EPA limits.
Violation history
Rosalia's water system has 88 total violations on record, including 7 health-based violations. 10 remain unresolved. 3 violations were issued in the last 5 years.
Flood & environmental risk
Whitman County has experienced 7 federally declared disasters since 1964. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies.
Where does Rosalia's water come from?
Rosalia's drinking water comes from groundwater (wells), supplied by 2 water systems serving approximately 1,046 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate.
What Rosalia residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Rosalia'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.
Rosalia'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
D2 — severe droughtWhitman County is currently in D2 (severe 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
Whitman County has experienced 7 federally declared disasters since 1964. 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. | 0.0 | 15 | ppb | Inorganic | Safe |
Lead level trend (90th percentile)
See how Rosalia compares by contaminant
Explore where Rosalia ranks among all Washington cities for specific contaminants.
Water source & infrastructure
Where Rosalia's water comes from
Rosalia'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 1,046 people through 2 water systems.
Water systems serving Rosalia
| System Name | PWSID | Population | Source |
|---|---|---|---|
| ROSALIA TOWN OF | WA5374250 | 831 | GW |
| MALDEN WATER DEPT | WA5350550 | 215 | GW |
How Rosalia compares
Full Washington rankings →Rosalia's score of 87.3/100 is above the average of 53/100 among major Washington cities. It outscores 9 of 10 nearby cities.
Nearby cities
View Washington rankings →About Rosalia, WA
Wikipedia →Rosalia is a town in Whitman County, Washington, United States. It is an agricultural community in the Palouse region, at an elevation of 2,238 feet (682 m) above sea level. Its population was 598 at the 2020 census.
Learn more about your water
Guides and resources related to Rosalia's water quality findings.
Explore water quality across Whitman
Frequently asked questions
Is Rosalia, WA tap water safe to drink?
Rosalia's water quality earned a grade of A- (87.3/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #77 out of 294 cities tested in Washington.
What contaminants are in Rosalia's water?
Lead was measured at 0.0 ppb (90th percentile). 88 violations are on record.
How is Rosalia'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 Rosalia?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Rosalia's water come from?
Rosalia's water is sourced from Groundwater. The city has 2 water systems serving approximately 1,046 residents.
What health violations has Rosalia's water system had?
Rosalia has 7 health-based violations on record. The most recent violation was recorded in January 2022. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 10 violations remain unresolved.
Is Rosalia's groundwater at risk of contamination?
Rosalia 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 88 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 Rosalia's water compare to other cities?
Rosalia ranks #77 out of 294 cities in Washington (better than 74% of state cities) and #4151 out of 15744 cities nationally (74th percentile). The grade of A- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.