01The verdict: is Lake Preston water safe?
Lake Preston's drinking water has significant quality concerns based on EPA testing data. With a grade of B (78.8/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 1 water system serves approximately 589 residents using groundwater (wells).
Copper is over its legal limit
Measured at 1.80 mg/L against the EPA Action Level of 1.3 mg/L. The ledger below shows how far over — and which filter removes it.
See the measurement ↓589 people, 1 system
All figures on this page come from federal EPA compliance and testing data for the systems serving this city.
See the systems ↓A flood-prone service area
10 federal disaster declarations on record. After severe weather, watch for boil-water advisories.
See the risk factors ↓Lake Preston's drinking water received a grade of B (78.8 out of 100), indicating good water quality. The city's 1 water system serves approximately 589 residents using purchased ground water.
Lead levels were measured at 7.0 ppb (90th percentile), which is within EPA limits but above recommended levels. This system has not yet been tested for PFAS under the EPA UCMR 5 program. The system has 17 violations on record, including 4 health-based violations. 8 remain unresolved.
Lake Preston ranks #105 out of 137 cities in South Dakota for water quality, placing it among the lowest-rated in the state. Lake Preston purchases its water from a regional wholesaler, meaning quality depends on both the supplier's treatment and the local distribution system's condition. While lead levels are within EPA limits, they are above the recommended 5 ppb threshold that health organizations consider ideal. A point-of-use filter adds an extra layer of protection. As a small community water system, Lake Preston may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
02What's in Lake Preston's water
Every contaminant flagged in Lake Preston, on one shared scale: distance to its own legal limit. The red line is the limit — anything past it is out of compliance, and the closer a bar gets, the less headroom the system has.
Over Limit — EPA Action Level: 1.3 mg/L
Exceeds the EPA action level. Copper leaches from household plumbing — flush taps for 30 seconds before drinking, and consider a certified filter.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. | 7.0 | 15 | ppb | Inorganic | Safe |
| Copper (90th percentile) CopperInorganic A metal that enters drinking water mainly through corrosion of copper plumbing. Small amounts are essential for health, but excess levels are harmful. Health EffectsGastrointestinal distress (nausea, vomiting, diarrhea) at short-term high levels; liver and kidney damage from long-term exposure. EPA Limit1.3 mg/L action level Common SourcesCorrosion of copper household plumbing, erosion of natural deposits. | 1.80 | 1.3 | mg/L | Inorganic | Over Limit |
Cities ranked by 90th-percentile lead PF PFAS in South Dakota
Cities ranked by compounds detected Cu Copper in South Dakota
Cities ranked by 90th-percentile copper
03Lake Preston's ten-year track record
Each box is one year. A green check means no EPA violations; a numbered badge counts that year's violations — red if any were health-based, amber if they were monitoring or paperwork issues. The system has 17 violations on record, including 4 health-based violations. 8 remain unresolved.
7 of the last ten years were clean. The numbered years had EPA violations — red when any were health-based, amber when they were paperwork or missed-testing issues.
▲ Up 3 ppb since 1993. Latest reading: 7 ppb (2024) — 47% of the action level. Sampled at higher-risk homes (90th percentile).
1.8mg/L(1993)
One sampling round on record — 138% of the 1.3mg/L EPA action level. Sampled at higher-risk homes (90th percentile).
04Where Lake Preston's water comes from
Lake Preston purchases its water supply from a regional wholesale provider rather than treating raw water directly.
Purchased Groundwater
Water is bought from a regional wholesaler; quality starts at the supplier's intake and treatment.
Wholesale supplier
Primary treatment happens at the wholesaler; the local utility maintains disinfectant residual in its pipes.
1 system
1 water system, operated under local government ownership.
589 people
Residents served across Lake Preston's service area.
Water quality depends on both the wholesaler's treatment standards and the condition of Lake Preston's local distribution pipes and storage facilities. Purchased water systems are common in suburban areas and smaller communities that lack the infrastructure for independent treatment. The system is operated by local government ownership and serves approximately 589 people through 1 water system.
| System name | PWSID | Population | Source |
|---|---|---|---|
| LAKE PRESTON | SD4600398 | 589 | Purchased Groundwater |
05Pressure on Lake Preston's watershed
Outside forces that shape what reaches the treatment plant. None of these is a verdict on the tap by itself — but each adds pressure worth knowing about.
Flood & storm history
10 federal disaster declarations on record for Kingsbury County. Flooding and severe storms can overwhelm treatment plants, cause sewage overflows, and push runoff into supplies.
Drought
Kingsbury County is in D1 (moderate drought) per the U.S. Drought Monitor (week of Jul 2026). Drought can raise disinfection-byproduct levels and taste/odor issues as utilities draw from lower reservoirs.
06How Lake Preston compares
Scores for nearby South Dakota cities on one line, with the average marked.
dashed line = South Dakota average (66/100)
Lake Preston scores 78.8/100 — above the South Dakota average of 66/100. It outscores 6 of 10 nearby cities. Full South Dakota rankings →
58.2 / 100FRapid City, SD
38.7 / 100FAberdeen, SD
41.8 / 100AWatertown, SD
91 / 100FPine Ridge, SD
43.2 / 100DBrookings, SD
46.2 / 100
Compare all cities in the county — grades, violations, and contaminant data side by side.→
07What to do at home
Steps matched to what testing actually found in Lake Preston's water — not generic advice.
Filter drinking & cooking water
NSF-certified water filter. Lead detected at 7.0 ppb
Compare tested filters →Flush taps & check your service line
Lead leaches from pipes as water sits. Run cold water 30 seconds before drinking (especially mornings), and ask the utility whether your address still has a lead service line.
Lead risks explained →Watch for Lake Preston alerts
This area has a history of flood declarations — after severe weather, watch for boil-water advisories from the utility, and check the live alerts on this page.
All water alerts →Frequently asked questions
Is Lake Preston, SD tap water safe to drink?
Lake Preston's water quality earned a grade of B (78.8/100). Some concerns have been identified. Consider a water filter for an extra layer of protection. The city ranks #105 out of 137 cities tested in South Dakota.
What contaminants are in Lake Preston's water?
Lead was measured at 7.0 ppb (90th percentile). 17 violations are on record.
How is Lake Preston'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 Lake Preston?
While lead levels are within EPA limits, a filter adds extra protection. Based on current data, basic filtration should suffice for additional peace of mind.
Where does Lake Preston's water come from?
Lake Preston's water is sourced from Purchased ground water. The city has 1 water system serving approximately 589 residents.
What health violations has Lake Preston's water system had?
Lake Preston has 4 health-based violations on record. The most recent violation was recorded in April 2020. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 8 violations remain unresolved.
Is Lake Preston's groundwater at risk of contamination?
Lake Preston 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 17 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 Lake Preston's water compare to other cities?
Lake Preston ranks #105 out of 137 cities in South Dakota (better than 23% of state cities) and #8423 out of 15382 cities nationally (45th percentile). The grade of B reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does Lake Preston's small water system affect quality?
Lake Preston's system serves approximately 589 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 17 violations on record.