Is Flagstaff, MO Tap Water Safe to Drink?
Graded D, with 68 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
47/100
waterverge.com Flagstaff, MO — Water Quality Report
Flagstaff's drinking water received a grade of D (47 out of 100), indicating poor water quality. The city's 2 water systems serve approximately 560 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 256 violations on record, including 18 health-based violations. 68 remain unresolved.
What to know about Flagstaff's water
Flagstaff ranks #484 out of 509 cities in Missouri for water quality, placing it among the lowest-rated in the state.
Flagstaff 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, Flagstaff may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
The system has seen 31 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Flagstaff, MO water safe to drink?
Flagstaff's drinking water has significant quality concerns based on EPA testing data. With a grade of D (47/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 2 water systems serve approximately 560 residents using groundwater (wells).
Recent water quality updates for Flagstaff
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Flagstaff's water quality assessment. Grade: D (47/100).
Contaminants: Lead and Copper Rule.
Contaminants: Arsenic, Consumer Confidence Rule.
Contaminants: Lead and Copper Rule.
Key contaminant findings
Based on the most recent EPA sampling data for Flagstaff's water supply.
Well within EPA limits.
Violation history
Flagstaff's water system has 256 total violations on record, including 18 health-based violations. 68 remain unresolved. 31 violations were issued in the last 5 years.
Where does Flagstaff's water come from?
Flagstaff's drinking water comes from groundwater (wells), supplied by 2 water systems serving approximately 560 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Creve Coeur Creek At Chesterfield (river), Creve Coeur Creek Near Creve Coeur (river), Fee Fee Creek Near Bridgeton (river), River Des Peres Near University City (river), River Des Peres Tributary At Pagedale (river).
What Flagstaff residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Flagstaff'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.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Violation summary
Violations & advisories
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 Flagstaff compares by contaminant
Explore where Flagstaff ranks among all Missouri cities for specific contaminants.
Water source & infrastructure
Where Flagstaff's water comes from
Flagstaff'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 public/private ownership and serves approximately 560 people through 2 water systems.
Water bodies near Flagstaff
Flagstaff is located near 5 notable water bodies. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Flagstaff
| System Name | PWSID | Population | Source |
|---|---|---|---|
| CS FLAGSTAFF RANCH WATER COMPANY | AZ0403088 | 350 | GW |
| CS WEST VILLAGE WATER COMPANY | AZ0403021 | 210 | GW |
How Flagstaff compares
Full Missouri rankings →Flagstaff's score of 47/100 is below the average of 62/100 among major Missouri cities. It outscores 4 of 10 nearby cities. 6 of 10 nearby cities score higher.
Nearby cities
View Missouri rankings →About Flagstaff, MO
Wikipedia →Des Peres is a city in west St. Louis County, Missouri, United States. The population was 9,193 at the 2020 census.
Learn more about your water
Guides and resources related to Flagstaff's water quality findings.
Explore water quality across Coconino
Frequently asked questions
Is Flagstaff, MO tap water safe to drink?
Flagstaff's water quality earned a grade of D (47/100). Significant issues have been found. A water filter is strongly recommended. The city ranks #484 out of 509 cities tested in Missouri.
What contaminants are in Flagstaff's water?
Lead was measured at 0.0 ppb (90th percentile). 256 violations are on record.
How is Flagstaff'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 Flagstaff?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Flagstaff's water come from?
Flagstaff's water is sourced from Groundwater. The city has 2 water systems serving approximately 560 residents.
What health violations has Flagstaff's water system had?
Flagstaff has 18 health-based violations on record. The most recent violation was recorded in October 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 68 violations remain unresolved.
Is Flagstaff's groundwater at risk of contamination?
Flagstaff 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 256 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 Flagstaff's water compare to other cities?
Flagstaff ranks #484 out of 509 cities in Missouri (better than 5% of state cities) and #13804 out of 15744 cities nationally (12th percentile). The grade of D reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.