Water in Oklahoma.
Oklahoma's reservoirs and shallow groundwater systems face arsenic and disinfection-byproduct exposure. Tar Creek Superfund area has decades of mining-related water contamination.
How Oklahoma regulates drinking water.
Federal SDWA primacy. No state MCLs stricter than federal. Tar Creek Superfund remains a long-running remediation case.
Oklahoma Department of Environmental Quality — Water Quality Division
Oklahoma's water history, in order.
The contamination events, regulatory shifts, and major settlements that define how this state thinks about drinking water today.
- 1983
Tar Creek (Picher) designated EPA Superfund site over lead and zinc mining contamination.
- 2018
Oklahoma City and Tulsa complete lead-service-line inventories ahead of federal mandate.
The actual water you drink.
The physical rivers, aquifers, lakes, and reservoirs that feed Oklahoma's public water systems. Source quality is the foundation of tap quality — and where the long-term protection fights happen.
- lakeLake Hefner + Lake Stanley Draper
Oklahoma City.
- lakeLake Murray + Arbuckle Aquifer
Southern OK.
- lakeLake Eufaula + Lake Tenkiller
Eastern OK.
Source-water mix
~70% surface water, ~30% groundwater
Major cities served
Oklahoma City · Tulsa · Norman · Broken Arrow
Who actually serves the water.
The largest public water systems in Oklahoma by population served. Click your ZIP after to see the full live EWG report for your specific utility.
- Oklahoma City Utilities DepartmentOklahoma City700Kserved
- City of Tulsa Water and SewerTulsa410Kserved
Where the contamination comes from.
Every state has a different industrial fingerprint. The industries below are the dominant historical and active contamination sources in Oklahoma's drinking water systems.
Tar Creek (Picher) Superfund — among the largest U.S. lead/zinc mining contamination zones. Oil-and-gas wastewater injection (induced seismicity) drives infrastructure concerns. Limited PFAS documentation compared to peer states.
What state data flags most consistently.
Drawn from EPA SDWIS sampling records, EWG state summaries, and regional regulatory action over the past five years. Read the full deep dive on each.
Arsenic
A naturally occurring carcinogen. Highest in private wells and the rural Southwest.
Trihalomethanes (TTHMs)
Byproducts of chlorinating water. Linked to bladder cancer at chronic exposure.
Nitrate
Fertilizer and animal waste runoff. Acutely dangerous for infants under 6 months.
Lead
A neurotoxic metal that leaches from old pipes and solder. No safe level for children.
Risk isn't evenly distributed.
Tar Creek-area residents (Ottawa County) face the most-documented mining-related contamination. Rural well users face arsenic.
~15% on private wells, concentrated in central and western OK.
What's coming for Oklahoma's water.
Drought cycles intensify, stressing reservoir storage and Arbuckle Aquifer recharge. Induced earthquakes (oil-and-gas wastewater injection) damaged groundwater infrastructure. Tornadoes regularly disable treatment plants.
Voluntary statewide
OK DEQ provides voluntary technical assistance.
Five questions for your next Consumer Confidence Report.
Your utility is required to send you a Consumer Confidence Report annually. Most are dense and procedural. These are the questions worth following up on for Oklahoma specifically.
- 1
If I'm in Ottawa County, is my well in the Tar Creek Superfund zone?
- 2
Has my utility had induced-seismicity-related infrastructure damage?
- 3
What is my system's PFAS testing status under the federal 2024 rule?
Most state regulators allow public records requests for the underlying lab reports behind your CCR — your utility should be able to provide them on request.
NSF/ANSI 58 reverse osmosis for arsenic, lead, and nitrate.
We don't recommend brands — the NSF/ANSI certification number matters more than the name on the box.
This is the state. Your address is the answer.
State-level patterns don't tell you about your specific tap. Run your ZIP for the live EWG contaminant report on your utility — or build a personalized Water File for your household.
Source-water mix, utility counts, lead-service-line estimates, and private-well shares are approximate, drawn from EPA SDWIS public data and state primacy-agency summaries. Contaminant rankings reflect EWG state-level monitoring data and regional regulatory action — they are not exhaustive. Timeline events are publicly documented. See methodology for the full sourcing. Search EPA SDWIS for Oklahoma