Is Gregory, 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 ↓
91.4/100
waterverge.com Gregory, SD — Water Quality Report
Gregory's drinking water received a grade of A (91.4 out of 100), indicating excellent water quality. The city's 1 water system serves approximately 1,221 residents using groundwater.
Lead levels were measured at 3.0 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 35 violations on record, including 2 health-based violations. 4 remain unresolved.
What to know about Gregory's water
Gregory ranks #29 out of 141 cities in South Dakota for water quality, placing it above average in the state.
Gregory 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.
Hexavalent chromium (chromium-6) was detected at 0.22 µg/L in UCMR 3 testing. While below California's 10 µg/L limit and with no federal MCL set, residents sensitive to this contaminant may consider reverse osmosis filtration.
As a small community water system, Gregory may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Water quality score
See methodology →Is Gregory, SD water safe to drink?
Gregory's drinking water has significant quality concerns based on EPA testing data. With a grade of A (91.4/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 1 water system serves approximately 1,221 residents using groundwater (wells).
Recent water quality updates for Gregory
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Gregory's water quality assessment. Grade: A (91.4/100).
Federal disaster declaration (FEMA DR-4807). Flood event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-4463). Flood event — may have impacted local water infrastructure.
1 health-based. Contaminants: Groundwater Rule.
Contaminants: Lead and Copper Rule.
1 health-based. Contaminants: Stage 1 Disinfectants and Disinfection Byproducts Rule.
Key contaminant findings
Based on the most recent EPA sampling data for Gregory's water supply.
Well within EPA limits.
Violation history
Gregory's water system has 35 total violations on record, including 2 health-based violations. 4 remain unresolved.
Flood & environmental risk
Gregory County has experienced 9 federally declared disasters since 1995. 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 Gregory's water come from?
Gregory's drinking water comes from groundwater (wells), supplied by 1 water system serving approximately 1,221 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate.
What Gregory residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Gregory'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.
Gregory'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
D3 — extreme droughtGregory County is currently in D3 (extreme 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
Gregory County has experienced 9 federally declared disasters since 1995. 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. | 3.0 | 15 | ppb | Inorganic | Safe |
Lead level trend (90th percentile)
See how Gregory compares by contaminant
Explore where Gregory ranks among all South Dakota cities for specific contaminants.
Water source & infrastructure
Where Gregory's water comes from
Gregory'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 1,221 people through 1 water system.
Water systems serving Gregory
| System Name | PWSID | Population | Source |
|---|---|---|---|
| GREGORY | SD4600145 | 1,221 | GW |
How Gregory compares
Full South Dakota rankings →Gregory's score of 91.4/100 is above the average of 66/100 among major South Dakota cities. It outscores 9 of 10 nearby cities.
Nearby cities
View South Dakota rankings →About Gregory, SD
Learn more about your water
Guides and resources related to Gregory's water quality findings.
Explore water quality across Gregory
Frequently asked questions
Is Gregory, SD tap water safe to drink?
Gregory's water quality earned a grade of A (91.4/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #29 out of 141 cities tested in South Dakota.
What contaminants are in Gregory's water?
Lead was measured at 3.0 ppb (90th percentile). 35 violations are on record.
How is Gregory'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 Gregory?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Gregory's water come from?
Gregory's water is sourced from Groundwater. The city has 1 water system serving approximately 1,221 residents.
What health violations has Gregory's water system had?
Gregory has 2 health-based violations on record. The most recent violation was recorded in January 2019. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 4 violations remain unresolved.
Is Gregory's groundwater at risk of contamination?
Gregory 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 35 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 Gregory's water compare to other cities?
Gregory ranks #29 out of 141 cities in South Dakota (better than 79% of state cities) and #1721 out of 15744 cities nationally (89th percentile). The grade of A reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does Gregory's small water system affect quality?
Gregory's system serves approximately 1,221 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 35 violations on record.