Is Cincinnati, OH Tap Water Safe to Drink?

Where Does Cincinnati Get Its Water?

Cincinnati's drinking water is supplied primarily by the Cincinnati Public Water System, which draws from the Ohio River as its source. The Ohio River is a surface water source, meaning it collects runoff and industrial discharge from a large upstream watershed before treatment begins.

Two major treatment plants serve the city: the Bolton Plant and the Miller Plant. Together they handle the bulk of water treatment before distribution to Cincinnati homes.

Norwood, a smaller city within the metropolitan area, receives water through its own public water system connected via a master meter arrangement. Cincinnati Children's Hospital operates a separate on-site treatment system for its campus, which is independent of the main residential supply.

How Is Cincinnati Tap Water Treated?

The Cincinnati Public Water System uses a multi-step treatment process. This includes coagulation, biological treatment, granular activated carbon filtration, ion exchange, and powdered activated carbon, which together remove a wide range of contaminants from Ohio River water before it reaches your tap.

Disinfection relies on free chlorine to kill bacteria and viruses, with ultraviolet light also used as an additional disinfection barrier. These steps protect against microbial risks and are why Cincinnati's water is generally safe from a bacterial standpoint.

The use of granular activated carbon and ion exchange is particularly relevant to PFAS removal. These technologies can reduce certain PFAS compounds, though recent testing shows some PFAS levels still exceed EPA's new standards in finished water.

What's in Cincinnati Tap Water?

The main concern in Cincinnati's tap water is PFOS, one of the most studied PFAS compounds. The highest detected level was 0.0061 micrograms per liter, above EPA's enforceable federal standard of 0.004 micrograms per liter. Detections above that standard appeared across 25 of the ZIP codes covered by this testing.

PFPeA, another PFAS compound, was detected at a peak of 0.0112 micrograms per liter against an EPA standard of 0.003 micrograms per liter, with one ZIP code showing a reading above that level. HFPO-DA (also known as GenX) was detected at up to 0.0063 micrograms per liter but did not exceed its benchmark in these samples. PFTrDA was also detected but remained at or below reporting thresholds without exceeding a guideline.

Lithium was detected across all 26 ZIP codes at a maximum of 9 micrograms per liter. There is currently no enforceable federal drinking water limit for lithium; this detection is noted for monitoring purposes but does not represent a regulatory violation. PFAS compounds in this water most likely originate from industrial and upstream sources in the Ohio River watershed.

Health Risk Profile for Cincinnati

PFOS and PFPeA are the primary concerns here. PFOS was measured at up to 0.0061 micrograms per liter, above EPA's 2024 federal standard of 0.004 micrograms per liter. Water systems have until 2031 to achieve full compliance, so elevated readings during this transition period are legally permitted for now but still worth understanding.

Infants, pregnant individuals, and people who are immunocompromised may face higher risks from PFAS exposure at any level. EPA set these standards specifically because long-term PFAS exposure has been linked to immune, hormonal, and developmental effects. For those groups, reducing exposure now rather than waiting for utility-level compliance is a reasonable choice.

A filter certified to NSF/ANSI 58 (reverse osmosis) or NSF/ANSI P473 (specifically tested for PFOA and PFOS removal) is the most effective option for reducing PFAS at the tap. NSF/ANSI is an independent third-party certification program, so look for that label on the box or the manufacturer's product page to confirm the filter has been independently tested.

For most healthy adults, the risk from short-term exposure at these levels is considered low by EPA. The science on PFAS health effects continues to evolve, and EPA has stated that no level of PFOS or PFOA exposure is without some risk. A filter is a practical step, not a panic measure.