By MATT BLOIS
Spring Hill has started investigating how to turn the water coming out of its wastewater treatment plant into drinking water.
The proposal to use treated wastewater in the drinking water supply is in its infancy and will take years before it becomes reality.
The city is in the very early stages of developing a plan to mix the water flowing out of the wastewater treatment plant with river water and send it through another treatment plant to produce drinking water. A statement from the city says it would use membrane filtration and ultraviolet light to ensure the safety of the water.
The National Research Council says this technology is safe, and can even be cleaner than traditional sources of water. Some cities in Texas have already implemented this kind of system, and more of these systems are planned in other states. Spring Hill could be the first to build one in Tennessee.
Tennessee doesn’t have any specific rules about reusing wastewater for drinking water, but it is currently developing some guidelines. Any plan to use wastewater in the drinking water supply would need approval from the state’s Department of Environment and Conservation.
The federal government regulates drinking water through the Safe Drinking Water Act and wastewater through the Clean Water Act. But it doesn’t have any specific rules about reusing wastewater. Cities are free to try creative ways to provide drinking water as long as they meet the standards set out in those acts and state specific standards.
The plan to use wastewater to supplement the city’s drinking water supply is a small part of a larger effort to provide enough water as the city expands. The city expects that by 2037 its water treatment plant will need to produce 10 million gallons of water on days with especially high demand.
The current water treatment plant can only produce about four million gallons of water per day, and the city only has a permit to draw six million gallons per day from the Duck River. Spring Hill is asking the Tennessee Department of Environment and Conservation for permission to draw more water out of the river, but there’s no guarantee that the city will get it.
Another option would be buying water from Columbia’s water system. The city already has a contract that allows it to buy almost three million gallons of water a day if necessary, but that arrangement expires next year. Columbia is also growing rapidly and might not be able supply that much water in the future.
A statement from the city of Spring Hill explained that that the city is trying to make use of the water that it already has as the demand for water increases. The city’s wastewater plant releases an average of about 3.5 million gallons of treated water every day.
The statement says taking advantage of that water was a cost effective way of producing safe drinking water.
Alex Gerling, a water reuse engineer for the American Water Works Association, said the technology to clean up wastewater has been around for years, and that the water from these systems is no more dangerous than water from a river.
“With all water sources it’s really important to have proper treatment and monitoring. Through that multiple barrier approach and the repeated treatment processes the water is treated to even higher standards,” she said. “When this is done properly it helps to remove the risks.”
The technology used to clean up wastewater isn’t all that different from what a normal water treatment plant does. Those technologies include physical filters, chemical treatments or ultraviolet light. Although, reusing wastewater could mean using more steps in the treatment process and combining those steps in new ways.
Reusing wastewater in the drinking water supply isn’t a new idea. Cities like Nashville, which draws its water from the Cumberland River, are already using some water discharged by wastewater treatment plants upstream.
In the city’s statement, Giles explained that most water treatment plants are already downstream from something or somebody. That includes Spring Hill.
“We are downstream of Lewisburg and Shelbyville, including the Tyson Foods (chicken) facility,” Giles said in the city’s statement.
The city already uses water from the wastewater treatment plant to irrigate golf courses and the community garden. But convincing people that putting treated wastewater into tap water will be a big challenge. There is an undeniable “ick factor” that the city will have to over come.
In the city’s statement, Giles explained that part of the reason the city is moving so slowly is to give the public confidence that the water will be safe.
According to a report from the Environmental Protection Agency, some communities employing wastewater reuse have been able to overcome the perception that recycled wastewater is gross.
Wichita Falls, Texas started reusing some of its wastewater during a severe drought in 2014. The report says the city didn’t receive any complaints while recycling their water, and some residents even said the water tasted better. Three Walmarts in the area reported that bottled water sales increased by about nine percent, but most people in town accepted the new technology.
Greg Kail, the director of communications for the American Water Works Association, said building support for these kinds of systems is a communications issue.
“The more familiar people are with a technology … the more confidence they have in the end product,” he said. “It’s going to take time in most of these circumstances to assure that people have the level of understanding necessary that they’ll accept it.”
That’s going to be a challenge for several cities in Williamson County will have as they explore similar options.
The City of Franklin is considering using some of its wastewater in the drinking water system indirectly by discharging its wastewater just upstream from its water treatment plant. That would put an environmental buffer between the wastewater discharge and the water treatment plant. Those types of systems are used widely across the country.
Franklin’s Assistant City Manager of Public Works Mark Hilty said that project is probably about a decade away, and the city hasn’t made any final decisions. He added that using wastewater directly isn’t off the table, but that the city will have to consider all of these options carefully before implementing any of them.
The Mayor of Thompson’s Station, Cory Napier, also said that his city would consider using wastewater in the drinking supply. He recently created a citizen committee to investigate options for the city’s sewer system. He said using some of that water for drinking water is an option.
Any plan to implement a system that reuses wastewater is likely many years away, but more and more communities are starting to use these systems. One study from a private water consulting firm estimated the wastewater reuse will increase by more than 60 percent between 2015 and 2025.
Part of the increasing interest in wastewater reuse is because of its reliability. It’s a source of water that cities can count on. After all, cities will always produce plenty of waste.