Keystone, SD Tap Water Quality 2026

Water quality report for Keystone, SD — PFAS, lead and copper results, violation history and state inspection findings from EPA SDWIS.

A look at Keystone's drinking water using EPA enforcement records: violations, lead and copper results, PFAS sampling and state inspection findings.

Main Utility: Keystone PWSID: SD4601082 Updated: 2026 Q2

✅

No federal limits exceeded on record

Lead is 2.00 ppb, 13% of the action level and no violations are open. PFAS has never been sampled at this system.

Keystone earns a C for water quality

Graded on violations and lead, with state inspection findings. PFAS not tested.

Lead: 2.00 ppb — 13% of the federal action level

PFAS never sampled at this system

6 violations since 2015, 3 health-based

No violations currently open

Keystone's lead level vs. all South Dakota community water systems

0 ppb5 ppb10 ppb15 ppb

Lead level: 2.00 ppb — 13% of the federal action level

✓ Lower lead than 63% of South Dakota utilities

Population Served

207

~249 connections

Water Source

Groundwater

Drawn from wells — SDWIS source code GW

Active Violations

6 since 2015, all resolved

Lead & Copper Testing

Lead (Pb)

90th percentile of tap samples collected across the distribution system

13% of EPA action level

2.00 ppb

Action level: 15 ppb

The 90th-percentile lead result is 2.00 ppb, 13% of the 15 ppb federal action level. The action level is a treatment trigger, not a legal maximum, and it is measured across sampled taps rather than at any single home.

Contaminant Violations (2015–Present)

Contaminant	Type	Measured	Limit	Period	Status
Gross Alpha, Excl. Radon and U	MONITORING AND REPORTING	—	15 pCi/L	2019	Resolved
Combined Radium (-226 and -228)	MONITORING AND REPORTING	—	5 pCi/L	2019	Resolved
Combined Uranium	MONITORING AND REPORTING	—	30 ug/L	2019	Resolved
Coliform (TCR)	MCL EXCEEDANCE	—	5% of samples	2015	Resolved
Coliform (TCR)	MCL EXCEEDANCE	—	5% of samples	2015	Resolved
Coliform (TCR)	MCL EXCEEDANCE	—	5% of samples	2015	Resolved

Understanding violation types MCL violations mean a contaminant exceeded the federal maximum limit — the most serious type.
TT (Treatment Technique) violations mean required treatment procedures weren't followed, but don't necessarily mean contamination occurred.

Violation History

6 violations are on record since 2015, of which 3 were health-based. All have been resolved and none remain open.

About the Main Water System

Utility Keystone

PWSID SD4601082

Water source Groundwater — Drawn from wells — SDWIS source code GW

Population served 207

Service connections 249

Systems serving this area 2

Regulator State primacy agency

Data through 2026 Q2 — EPA SDWIS

Frequently Asked Questions

Is Keystone tap water safe to drink? ▼

No federal limit is exceeded on record. No violations are currently open. Lead is 2.00 ppb, 13% of the action level.

Does Keystone water have PFAS? ▼

This system has never been sampled for PFAS. EPA's national monitoring covered systems serving 3,300 people or more, so no results exist — which is not evidence that none is present.

Who supplies water to Keystone? ▼

Keystone (PWSID SD4601082), one of 2 systems serving this area. Groundwater. Drawn from wells — SDWIS source code GW

When was this system last inspected? ▼

It was last inspected on 2024-10-15. Inspectors recorded 2 significant deficiencies.

What Should Keystone Residents Do?

Read your annual water report

Your supplier publishes a Consumer Confidence Report each July covering the prior year.

Check for a lead service line

Lead reaches tap water mainly through service lines and household plumbing. Suppliers now publish an inventory identifying lead lines.

Flush before drinking

If water has sat in pipes more than six hours, run the cold tap for two minutes before drinking or cooking.

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