What's The Data On Wastewater For Data?

Could Treated Wastewater Cool Stark County Data Centers Without Straining Drinking Water Supplies?

Data centers need two things in very large quantities: electricity and water. Those also happen to be the two things that have caused some of the greatest public concern as large data center projects move closer to Stark County. That raises a practical question. If millions of gallons of treated wastewater are already leaving local treatment plants every day, could some of that water be used for cooling data centers instead of pulling more drinking water from the public supply?

During Monday’s Massillon City Council meeting, Mayor Jamie Slutz raised the possibility of supplying future data centers with treated water from the city’s wastewater treatment facility. The idea was discussed as a possibility rather than a finalized proposal, and no agreement, customer or specific water volume has been announced.

Using treated wastewater for industrial cooling is not a new concept. The United States Environmental Protection Agency says properly treated municipal wastewater can be used as cooling water for data centers, potentially reducing pressure on drinking water supplies. EPA is also developing additional guidance intended to help states permit recycled water systems for industrial and data center cooling.

The water being discussed is not raw sewage. It is wastewater that has passed through a municipal treatment facility and is normally released into a river or stream as treated effluent. That distinction is important because the water is already part of the normal flow entering local waterways.

Canton operates a much larger wastewater system than Massillon. Canton’s Water Reclamation Facility has an average design flow of 39 million gallons per day and a maximum daily design flow of 88 million gallons. A November 2025 Ohio EPA environmental review said approximately 27 million gallons per day was flowing into the facility at that time. That equals roughly 810 million gallons during a 30 day month. However, the 27 million gallon figure measures water entering the facility and should not be treated as a confirmed measurement of the amount leaving through the final outfall.

After treatment, Canton releases its effluent into Nimishillen Creek at River Mile 10.0. The water then travels through Sandy Creek before reaching the Tuscarawas River, followed by the Muskingum River and ultimately the Ohio River. Canton therefore does not discharge its normal treated wastewater directly into the Tuscarawas River.

Massillon’s wastewater facility has an average design flow of 17 million gallons per day and a peak hydraulic capacity of 22 million gallons per day. Unlike Canton, Ohio EPA’s current Massillon permit fact sheet provides recent measurements for the final treated discharge. Massillon’s final outfall averaged 10.98 million gallons per day in 2024. During the 273 days represented in the 2025 data, the average was 11.57 million gallons per day. Those rates equal approximately 329 million to 347 million gallons during a 30 day month.

Massillon releases its treated wastewater directly into the Tuscarawas River at River Mile 88.87. Its treatment process includes biological nutrient removal, phosphorus removal, secondary clarification, disk filtration and ultraviolet disinfection before normal final effluent reaches the river.

Those numbers demonstrate that a substantial volume of treated water moves through the two facilities, but they do not establish how much could be supplied to data centers. Actual flows change with weather, sewer use and seasonal conditions. A future reuse system would also need to account for the amount of water consumed through evaporation, the amount recirculated and the amount eventually returned to the sewer system or discharged elsewhere.

One potential advantage would be reducing the use of potable water for cooling. EPA says recycled water can provide an industrial water supply without placing the same demand on water intended for homes and businesses. In Quincy, Washington, Microsoft and the city constructed a specialized system that treats and recirculates data center cooling water. EPA estimates that system reduces reliance on potable groundwater by approximately 138 million gallons annually.

That example also shows that reuse is more complicated than simply running a pipe from a wastewater plant to a data center. Water used in cooling systems can become more concentrated with minerals as part of it evaporates. The Quincy system uses lime softening, ultrafiltration and reverse osmosis, while concentrated salts and other residuals are separated for disposal. The local treatment requirements would depend on the quality of Canton or Massillon’s effluent and the cooling system selected by a developer.

The environmental effects of removing treated effluent from local waterways have not yet been determined. Treated wastewater can represent an important portion of a river or stream’s flow, particularly during dry weather. The United States Geological Survey has noted that wastewater effluent is commonly returned to streams and may help sustain minimum flows for ecological purposes. Another USGS study described municipal and industrial effluent as an important source of water for streams during low flow periods.

If a significant amount of Canton’s discharge were diverted, Nimishillen Creek could receive less water downstream of the treatment plant. Depending on how much of the creek’s dry weather flow comes from the facility, a reduction could potentially change water depth, velocity, temperature, available aquatic habitat and the creek’s ability to dilute other pollution. The effect cannot be determined from the plant’s flow figures alone. It would require comparison of the proposed diversion with seasonal stream measurements, particularly during drought and low flow conditions.

The same questions would apply to the Tuscarawas River below Massillon, although the size and natural flow of the receiving water are different. The environmental importance of a diversion would depend less on the total number of gallons and more on what percentage of the river’s flow those gallons represent at different times of the year.

There could also be environmental benefits. Sending less wastewater into a creek or river may reduce the total amount of nutrients and other remaining contaminants entering the waterway. EPA identifies reduced nutrient discharges as one potential benefit of water reuse. The final result could therefore involve a tradeoff between lower pollutant loading and reduced streamflow.

Both receiving waterways already have documented water quality concerns. Ohio EPA lists the portion of Nimishillen Creek near Canton as impaired for aquatic life because of nutrient enrichment and habitat impairment. The Tuscarawas River segment near Massillon is listed as impaired for recreational and human health uses because of E. coli, PCBs and hexachlorobenzene. Those conditions do not prove that water reuse would make either stream better or worse, but they make a detailed environmental review important before a large portion of either discharge is redirected.

Another major question is what happens to the water after it reaches a data center. A largely closed system could repeatedly circulate the water while replacing what is lost through evaporation. A different design might send cooling water or concentrated blowdown back to the municipal sewer system. A system that creates a new discharge into a river or stream could require additional treatment and environmental permitting. EPA guidance says cooling water and blowdown discharged to surface water are subject to wastewater permitting requirements.

The idea may ultimately make sense. But before anyone celebrates millions of gallons of available water, it would be wise to remember that the water is not currently sitting unused.

It is already doing something. It is flowing into Nimishillen Creek and the Tuscarawas River.

The question is whether it can do another job without creating a different problem somewhere farther down the line.

The Ohio EPA and representatives for both cities had not responded before publication to questions about the potential environmental effect of diverting treated discharge from Nimishillen Creek or the Tuscarawas River. Responses or additional information from Canton, Massillon and Ohio EPA will be added when received.