Water in Ohio.
Lake Erie supplies most of northern Ohio. The 2014 Toledo algal-bloom crisis left 500,000 residents without tap water for three days. East Palestine's 2023 train-derailment chemical contamination remains an active concern. PFAS plumes from DuPont's Washington Works in Parkersburg affect Ohio River systems.
Toledo's 2014 microcystin shutdown was the first major U.S. tap water crisis caused by algal blooms.
How Ohio regulates drinking water.
Federal SDWA primacy. Post-Toledo, statewide harmful-algal-bloom monitoring program. PFAS Action Plan adopted 2020.
Ohio Environmental Protection Agency — Division of Drinking and Ground Waters
Ohio's water history, in order.
The contamination events, regulatory shifts, and major settlements that define how this state thinks about drinking water today.
- 2014
Toledo's Microcystin shutdown — 500,000 residents lose tap water for 3 days due to Lake Erie algal bloom.
- 2020
Ohio EPA launches PFAS Action Plan with statewide community-system sampling.
- 2023
East Palestine train derailment releases vinyl chloride and other chemicals; long-term groundwater monitoring ongoing.
The actual water you drink.
The physical rivers, aquifers, lakes, and reservoirs that feed Ohio's public water systems. Source quality is the foundation of tap quality — and where the long-term protection fights happen.
- lakeLake Erie
Toledo, Cleveland, NW Ohio — major HAB source.
- riverOhio River
Cincinnati supply.
- riverGreat Miami River + Aquifer
Dayton metro.
- riverScioto River
Columbus area.
Source-water mix
~75% surface water, ~25% groundwater
Major cities served
Columbus · Cleveland · Cincinnati · Toledo · Akron · Dayton
Who actually serves the water.
The largest public water systems in Ohio by population served. Click your ZIP after to see the full live EWG report for your specific utility.
- City of Columbus Department of Public UtilitiesColumbus1,200Kserved
- Cleveland WaterCleveland metro1,500Kserved
- Greater Cincinnati Water WorksCincinnati metro1,100Kserved
- City of Toledo Public UtilitiesToledo500Kserved
Where the contamination comes from.
Every state has a different industrial fingerprint. The industries below are the dominant historical and active contamination sources in Ohio's drinking water systems.
DuPont Washington Works (Parkersburg WV) PFAS plumes affect Ohio River systems. East Palestine 2023 train derailment (vinyl chloride) contaminated multiple watersheds. Legacy steel and tire manufacturing in Akron, Youngstown, Cleveland drives chromium and PCB contamination.
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.
Lead
A neurotoxic metal that leaches from old pipes and solder. No safe level for children.
PFAS (Forever Chemicals)
A class of ~15,000 synthetic chemicals that don't break down. Now regulated for the first time.
Trihalomethanes (TTHMs)
Byproducts of chlorinating water. Linked to bladder cancer at chronic exposure.
Chromium-6 (Hexavalent Chromium)
The Erin Brockovich chemical. A known carcinogen with no federal-specific limit yet.
Risk isn't evenly distributed.
Toledo and Lake Erie shoreline residents face recurring HAB risk. East Palestine and surrounding areas face derailment-related long-term contamination. Ohio River cities face PFAS.
~15% on private wells, mostly rural eastern and southern Ohio.
What's coming for Ohio's water.
Lake Erie harmful algal bloom (microcystin) intensifies with agricultural runoff and warming — the Toledo 2014 shutdown remains the defining U.S. HAB tap-water event. Ohio River algal bloom risk increases. Extreme rainfall stresses combined sewer systems.
Voluntary statewide
Ohio EPA provides voluntary technical assistance; major districts have voluntarily tested.
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 Ohio specifically.
- 1
If I'm on the Lake Erie shoreline, has my utility activated HAB-related advisories this season?
- 2
If I'm in East Palestine or downstream, has my private well been tested for vinyl chloride?
- 3
What is my Cincinnati / Ohio River utility's PFAS testing status?
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.
What's changed in Ohio water law.
Drinking water regulation moves at the state level as much as the federal level. Below are notable recent bills and regulatory actions specific to Ohio.
- 2023
East Palestine Water Quality Monitoring Act (state and federal coordination).
- 2020
Ohio PFAS Action Plan launched.
For algal toxins: NSF/ANSI 53 + 401. For PFAS: NSF/ANSI P473. For East Palestine vinyl chloride concerns: NSF/ANSI 53 certified for VOC reduction.
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 Ohio