Is Onida, SD Tap Water Safe to Drink?
Graded A-, with 4 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
88.7/100
waterverge.com Onida, SD — Water Quality Report
Onida's drinking water received a grade of A- (88.7 out of 100), indicating good water quality. The city's 1 water system serves approximately 658 residents using purchased surface water.
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 66 violations on record, including 16 health-based violations. 4 remain unresolved.
What to know about Onida's water
Onida ranks #47 out of 141 cities in South Dakota for water quality, placing it mid-range in the state.
The city draws from surface water sources, which are more susceptible to seasonal runoff and agricultural contamination, requiring extensive multi-barrier treatment including coagulation, filtration, and disinfection.
As a small community water system, Onida may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Water quality score
See methodology →Is Onida, SD water safe to drink?
Onida's drinking water has significant quality concerns based on EPA testing data. With a grade of A- (88.7/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 1 water system serves approximately 658 residents using surface water (rivers, lakes, or reservoirs).
Recent water quality updates for Onida
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Onida's water quality assessment. Grade: A- (88.7/100).
Federal disaster declaration (FEMA DR-4440). Flood event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-1984). Flood event — may have impacted local water infrastructure.
Contaminants: Public Notice.
Contaminants: Coliform (TCR).
Contaminants: Consumer Confidence Rule.
Key contaminant findings
Based on the most recent EPA sampling data for Onida's water supply.
Well within EPA limits.
Violation history
Onida's water system has 66 total violations on record, including 16 health-based violations. 4 remain unresolved.
Flood & environmental risk
Sully County has experienced 7 federally declared disasters since 1986. 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 Onida's water come from?
Onida's drinking water comes from surface water (rivers, lakes, or reservoirs), supplied by 1 water system serving approximately 658 people. Surface water sources are more susceptible to contamination from runoff, industrial discharge, and algal blooms, requiring extensive treatment.
What Onida residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Onida'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.
Onida'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 Onida
Industrial polluters nearby
Reported releases to surface water by facilities near Onida, ranked by pounds discharged annually.
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
RING-NECK ENERGY & FEED LLC ONIDA, SD57564 | — | — | 0.7 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Flood & disaster history
Sully County has experienced 7 federally declared disasters since 1986. 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 Onida compares by contaminant
Explore where Onida ranks among all South Dakota cities for specific contaminants.
Water source & infrastructure
Where Onida's water comes from
Onida's drinking water comes primarily from surface water sources such as rivers, lakes, or reservoirs.
Surface water systems require multi-stage treatment including coagulation, sedimentation, filtration, and disinfection to meet EPA Safe Drinking Water Act standards.
These sources can be impacted by seasonal changes, stormwater runoff, upstream agriculture, and industrial discharge.
The system is operated by local government ownership and serves approximately 658 people through 1 water system.
Water systems serving Onida
| System Name | PWSID | Population | Source |
|---|---|---|---|
| ONIDA | SD4600233 | 658 | SWP |
How Onida compares
Full South Dakota rankings →Onida's score of 88.7/100 is above the average of 66/100 among major South Dakota cities. It outscores 8 of 10 nearby cities.
Nearby cities
View South Dakota rankings →About Onida, SD
Wikipedia →Onida is a city in and the county seat of Sully County, South Dakota, United States. The population was 666 as of the 2020 census.
Learn more about your water
Guides and resources related to Onida's water quality findings.
Explore water quality across Sully
Frequently asked questions
Is Onida, SD tap water safe to drink?
Onida's water quality earned a grade of A- (88.7/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #47 out of 141 cities tested in South Dakota.
What contaminants are in Onida's water?
Lead was measured at 2.0 ppb (90th percentile). 66 violations are on record.
How is Onida'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 Onida?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Onida's water come from?
Onida's water is sourced from Purchased surface water. The city has 1 water system serving approximately 658 residents.
What health violations has Onida's water system had?
Onida has 16 health-based violations on record. The most recent violation was recorded in August 2004. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 4 violations remain unresolved.
How does Onida's water compare to other cities?
Onida ranks #47 out of 141 cities in South Dakota (better than 67% of state cities) and #3326 out of 15744 cities nationally (79th percentile). The grade of A- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does Onida's small water system affect quality?
Onida's system serves approximately 658 residents. Small community water systems (under 3,300 people) may have fewer financial resources for infrastructure upgrades and advanced treatment technologies. However, they are held to the same EPA drinking water standards as larger systems. This system has 66 violations on record.