Cincinnati – Ohio
Greater Cincinnati Water Works (GCWW) serves over 1.1 million customers across the greater Cincinnati metropolitan area, including Hamilton County and parts of Butler, Warren, Clermont, and Boone counties. The utility manages approximately 3,000 miles of water mains, two major drinking water treatment plants, and multiple reservoirs, delivering an average of 133 million gallons daily to this historic Ohio River city.
Cincinnati draws its drinking water primarily from the Ohio River (85% of supply) and the Great Miami Aquifer (15% of supply), providing both surface and groundwater sources for enhanced reliability. GCWW operates the Richard Miller Treatment Plant for river water and the Bolton Treatment Plant for groundwater, creating a dual-source system with exceptional resilience. Cincinnati has earned international recognition for water quality excellence, particularly for its pioneering use of granular activated carbon and UV disinfection technologies. The city has invested over $1.5 billion in water infrastructure improvements since 2000, focusing on treatment advancements, distribution system upgrades, and source water protection to ensure safe, reliable drinking water for this major Midwest urban center.
Cincinnati Water Quality: Current Status (2024-2025)
Latest Testing Results
- Lead Levels: The most recent testing period (January-December 2023) showed 90th percentile lead levels of 3.1 parts per billion (ppb), significantly below the EPA action level of 15 ppb, reflecting Cincinnati’s industry-leading corrosion control program and extensive lead service line replacement initiatives.
- Testing Scope: GCWW conducts over 200,000 water quality tests annually, monitoring more than 250 potential contaminants through its comprehensive Quality Water Analysis program that exceeds federal and state requirements.
- Compliance Status: Cincinnati’s water meets or exceeds all federal and state drinking water standards, maintaining perfect compliance with EPA and Ohio EPA regulations for 29 consecutive years.
Dual-Source Water Supply
- Ohio River: Primary source (approximately 85% of supply) with intake points strategically located upstream of the metropolitan area to minimize urban impact on source water quality.
- Great Miami Aquifer: Secondary source (approximately 15% of supply) providing naturally filtered groundwater through deep wells, offering reliability during river quality challenges or drought conditions.
- Watershed Protection: Active participation in the Ohio River Valley Water Sanitation Commission (ORSANCO) and source water protection partnerships spanning multiple states to monitor and protect water quality throughout the watershed.
Advanced Treatment Excellence
- Multi-Barrier Treatment: Richard Miller Treatment Plant employs advanced processes including clarification, granular activated carbon filtration, UV disinfection, and chloramine treatment to address a broad spectrum of potential contaminants.
- Granular Activated Carbon: Cincinnati pioneered the large-scale use of GAC technology, which effectively removes organic compounds, pharmaceuticals, PFAS, and taste/odor compounds through adsorption.
- Enhanced Corrosion Control: Industry-leading orthophosphate treatment program prevents lead and copper leaching from pipes, with optimization based on comprehensive water chemistry monitoring throughout the distribution system.
Infrastructure Investment
- Capital Improvement Program: Over $1.5 billion invested in water system upgrades since 2000, addressing aging infrastructure, treatment enhancements, and system expansion to meet regional growth.
- Lead Service Line Replacement: Comprehensive program that has removed over 15,000 lead service lines since 2016, with a target of complete replacement of all customer-owned and utility-owned lead connections by 2032.
- Smart Water Technology: Implementation of advanced metering infrastructure, predictive maintenance systems, and real-time water quality monitoring to optimize system performance and quickly address emerging issues.
River Management and Climate Resilience
Cincinnati has developed a forward-looking approach to water management considering the unique challenges of the Ohio River system. GCWW’s “Water Supply Master Plan” addresses both drought vulnerabilities and flood impacts, with specific attention to changing precipitation patterns in the Ohio River Basin. The utility has implemented early warning systems for river contamination events, including enhanced real-time monitoring stations at strategic locations upstream of water intakes. Cincinnati’s treatment facilities have been designed with built-in redundancy and operational flexibility to handle fluctuations in river water quality during extreme weather conditions. The city’s dual-source approach enhances resilience, allowing seamless transitions between river water and groundwater during challenging river conditions or in response to upstream spill events, ensuring continuous delivery of safe drinking water regardless of environmental changes.
Recommendations for Cincinnati Residents
Check Your Service Line
Use GCWW’s online tool or call (513) 591-7700 to determine if your home has a lead service line. Cincinnati offers free lead testing kits and provides generous financial assistance for lead service line replacements, covering up to 70% of replacement costs.
Filter If Necessary
If you have a lead service line or older plumbing, use NSF-certified filters (Standard 53) for drinking and cooking water. GCWW provides free pitcher filters to eligible households with documented lead service lines or elevated lead levels during construction periods.
Participate in Conservation
Take advantage of Cincinnati’s water conservation incentives, including rebates for water-efficient appliances and fixtures. GCWW’s sustainable water use program offers free irrigation assessments and rain barrel workshops to promote responsible water stewardship.
Flush After Home Plumbing Work
After any plumbing work or extended periods of non-use (one week or more), run cold water for 3-5 minutes to flush stagnant water from pipes. For homes with lead service lines, GCWW recommends a more thorough 15-minute flushing process available on their website.
Sign Up for Alerts
Register for GCWW’s customer notification system to receive timely alerts about water main breaks, planned service disruptions, or other water quality advisories in your specific area. Alerts are available via text message, email, or phone call based on your preferences.
Frequently Asked Questions
Is Cincinnati’s tap water safe to drink?
Yes, Cincinnati’s tap water consistently meets or exceeds all federal and state drinking water standards and is internationally recognized for its exceptional quality. The city’s water undergoes extensive treatment at our Richard Miller Treatment Plant, including multiple purification barriers such as clarification, granular activated carbon filtration, UV disinfection, and chloramine treatment.
GCWW conducts over 200,000 water quality tests annually, monitoring for more than 250 potential contaminants with a laboratory that holds certification for 17 different analytical methods. Cincinnati has maintained perfect compliance with EPA standards for nearly three decades and has been recognized by the Partnership for Safe Water for its outstanding treatment processes.
Cincinnati’s pioneering use of granular activated carbon provides superior protection against emerging contaminants, including pharmaceuticals, PFAS compounds, and industrial chemicals. During Ohio River quality variations, our advanced monitoring systems detect changes quickly, allowing immediate treatment adjustments to maintain water quality, and we can switch to our Great Miami Aquifer source if necessary.
How does Cincinnati manage Ohio River water quality variations?
Cincinnati employs a multi-faceted approach to manage Ohio River water quality fluctuations:
• Early Warning System: GCWW operates an extensive network of real-time monitoring stations upstream of our water intakes to provide advance notice of any water quality changes
• Adaptable Treatment: The Richard Miller Treatment Plant can rapidly adjust treatment processes based on incoming water quality, with automated systems that optimize chemical dosing and filtration
• Source Water Switching: During significant river quality challenges, GCWW can transition to its groundwater source from the Great Miami Aquifer
• Regional Collaboration: Active participation in ORSANCO and the Ohio River Drinking Water Protection Network enables coordinated responses to watershed events
• Advanced Treatment Barriers: Multiple treatment processes provide redundant protection, with granular activated carbon and UV disinfection offering exceptional capability to address a wide range of potential contaminants
These systems have successfully maintained water quality through major river events, including floods, droughts, algal blooms, and upstream industrial spills.
What is Cincinnati doing about lead service lines?
Cincinnati has implemented one of the nation’s most progressive lead service line replacement programs:
• Enhanced Inventories: GCWW has mapped over 40,000 service lines across the system through historical records review, predictive modeling, and field verification
• Replacement Program: Since 2016, over 15,000 lead service lines have been replaced, with an accelerated timeline targeting complete system-wide replacement by 2032
• Financial Assistance: Property owners can receive up to 70% of replacement costs through GCWW’s assistance program, with enhanced support for low-income households
• Free Testing: Cincinnati offers complimentary lead testing kits to all customers upon request
• Coordinated Construction: Lead line replacements are synchronized with street and infrastructure projects to minimize disruption and maximize efficiency
• Industry-Leading Corrosion Control: Optimized orthophosphate treatment effectively prevents lead leaching from remaining lead service lines while replacement work continues
This comprehensive approach has resulted in consistently low lead levels in Cincinnati’s water, with recent testing showing levels of just 3.1 ppb—well below the EPA action level of 15 ppb.
Why is Cincinnati’s water treatment considered advanced?
Cincinnati has earned international recognition for its pioneering water treatment approaches:
• Granular Activated Carbon: Cincinnati was one of the first major utilities to implement large-scale GAC filtration in 1992, which provides superior removal of organic compounds, pharmaceuticals, PFAS, pesticides, and taste/odor compounds
• UV Disinfection: In 2013, GCWW added one of the largest drinking water UV treatment facilities in North America, providing additional protection against chlorine-resistant microorganisms like Cryptosporidium and Giardia
• Multi-Barrier Approach: Treatment includes coagulation, flocculation, sedimentation, sand filtration, GAC, UV disinfection, and chloramine disinfection—creating multiple protective barriers against various contaminants
• Research Partnerships: GCWW maintains an active research program with the EPA, Water Research Foundation, and regional universities to evaluate emerging treatment technologies and water quality challenges
• Real-Time Monitoring: Advanced sensor networks throughout the treatment process allow immediate adjustments based on changing water conditions
These innovative approaches have established Cincinnati as a national leader in water treatment technology and consistently earn GCWW recognition for exceptional water quality.
Contaminants of Concern
PFAS Compounds
Source: Industrial processes, firefighting foams, and consumer products that may enter the Ohio River watershed from multiple states upstream of Cincinnati
Health Effects: Potential links to increased cholesterol levels, changes in liver enzymes, decreased vaccine response in children, and increased risk of certain cancers with long-term exposure to high levels
Current Status: Cincinnati’s granular activated carbon filtration system effectively removes most PFAS compounds to levels well below EPA’s proposed regulatory limits; GCWW has conducted extensive PFAS monitoring since 2013, consistently finding treated water levels significantly below health advisory levels
Lead
Source: Lead service lines and older plumbing materials in homes built before 1986; Cincinnati has identified approximately 25,000 remaining lead service connections out of an original 40,000+ connections
Health Effects: Developmental delays in children, reduced IQ, learning difficulties, kidney problems, and cardiovascular effects in adults
Current Levels: 90th percentile value of 3.1 ppb, well below EPA action level of 15 ppb EPA Limit: Action level 15 ppb, but no level of lead is considered safe
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