WaterQ

South Dakota Tap Water Quality Rankings 2026: 6th in Nation | WaterQ

Alex Carter
By Alex Carter
Water Quality Researcher ยท Published 2026-06-23

South Dakota ranks 6th out of 50 states for drinking water quality, receiving an average score of 91 and an overall grade of A. The state manages 115 water systems serving a population of 834,433. While the state's overall grade is high, tracking local drinking water safety remains important for residents.

Key Findings for South Dakota

Reviewing EPA SDWIS data for 2026, here's what defines South Dakota's water quality landscape:

  • Given its location in the agricultural Great Plains region, South Dakota's water systems can be vulnerable to runoff containing fertilizers, which can elevate nitrate levels.
  • Because much of the state is groundwater-dependent, naturally occurring geologic minerals like arsenic can sometimes affect local source water quality.
  • With 115 water systems and 3,184 reported violations, maintaining compliance and monitoring infrastructure remains a key priority across systems.

Most Common Contaminants in South Dakota

Here's what South Dakota residents should know about the contaminants most relevant to their water:

Nitrate

Commonly introduced through agricultural activities and fertilizer use in the Great Plains, nitrates can leach into groundwater resources.

Arsenic

As a groundwater-dependent state, South Dakota's aquifers may contain naturally occurring arsenic dissolved from bedrock geology.

Total Coliform

Often monitored as an indicator of potential bacterial pathways, total coliform is a key concern for rural groundwater systems and private wells.

South Dakota's Best and Worst Cities for Water Quality

For a detailed look at how water quality varies by community, residents can access our complete city-by-city breakdown on the South Dakota state page. This data highlights specific compliance histories and test results for local water systems across the state. Explore the full breakdown on our South Dakota water systems page.

What South Dakota Residents Should Do

Given South Dakota's 6th place ranking, here's what matters most for residents:

  1. Search your local water system's Consumer Confidence Report (CCR) for annual testing results.
  2. Test private wells regularly for common local contaminants like nitrates and bacteria, as private wells are not regulated by the EPA.
  3. Consider installing a water filtration system certified to reduce the specific contaminants found in your local supply.
  4. Check the EPA's Enforcement and Compliance History Online (ECHO) database for any recent violations in your water system.

Frequently Asked Questions

How does South Dakota water quality compare to other states?

South Dakota ranks 6th out of 50 states in drinking water quality. It holds an average score of 91, which earns it an overall grade of A.

What are the most common contaminants in South Dakota tap water?

Common contaminants monitored in South Dakota include nitrates from agricultural activities, naturally occurring arsenic in groundwater, and bacteria like total coliform.

Is it safe to drink tap water in South Dakota?

With an overall grade of A, South Dakota's public water systems generally maintain high compliance with safety standards. However, localized violations can occur, and residents using private wells should conduct independent testing to ensure safety.

Source: EPA SDWIS 2026 Compliance Data and WaterQ National Database. For more information on our ranking process, visit our state rankings page.