An environmental engineer and professor emeritus at the University of Florida with decades of experience in water reclamation and regulation said there are risks involved with converting highly-treated reclaimed water to drinking water, but some of those same risks already exist in our current hydrologic system.
JEA is in the first phase of a pilot program converting treated reclaimed water — that once ran through city sewers — into drinking water that would flow out of your tap. The three-phase project began in 2016 because technology for these treatments has become increasingly affordable.
Joseph Delfino said large scale operations purifying so-called gray water for human consumption has proven a reliable way to beef up conservation in areas with water shortages, but that doesn’t mean it won’t come with its own set of complications, two to be exact.
The first is that even after formerly-sewer water is run through a reverse osmosis process or some kind of biological filter, it still has to be treated with agents like fluoride or chlorine. The latter, Delfino said, can prove problematic if there is some kind of contamination unrelated to the original treatment process.
“If you add chlorine after all of your filtration, you’re not going to make disinfection byproducts hardly at all at that point, but as the water moves through the piping system to the individual homes, if there is any organic matter infiltrating in the system — it doesn’t have to be a lot — the chlorine that’s added as a disinfection agent will react with it and form disinfection byproducts at some low levels,” he said.
These byproducts aren’t found at levels high enough to cause harm to humans, but Delfino said if there’s a breach somewhere in the drinking water delivery system, like a crack in a utility pipe, the concentration of these byproducts could cause problems for individuals farther down the water source line. Continuous exposure to high levels of these byproducts has been shown to cause cancers, Delfino said.
Secondly, Delfino said even with the best filtration system coupled with copious amounts of chlorine, parasites delivered through fecal coliform found in human or animal waste can sneak through and wreak havoc.
“When chlorine is used, and again either as gaseous chlorine or bleach which is hypochlorite — just the other side of the chlorine dissolving in water — it does a [good] job of killing most, but not all biological agents,” he said. “It doesn’t do a good job on some parasites.”
Delfino said the most severe real world example of this possibility came 25 years ago in Milwaukee, Wisconsin. It was the largest waterborne disease outbreak ever documented in United States. Although the cause of the parasitic protozoan outbreak was never officially discovered, it’s widely believed it began when cattle runoff leached into the ground and melting snow carried cryptosporidium to Lake Michigan where area water treatment plants treated and then sent the water to residents.
Delfino acknowledges the potential for that kind of outbreak is slim, and he said it already exists, even without the advent of wastewater/drinking water conversion, something that would require state approval before it moves ahead.
“So, it’s kind of strange that… people are concerned about taking water out of the ground after it had been sewage that was well-treated, pumped into the ground and then pumped back up again, treated again and put into the drinking water supply,” he said. “In fact the only difference is that in Orlando they treat water from the wastewater treatment plant, run it through a wetland and then it becomes part of the water flowing in the St. Johns [River] as it heads north to Jacksonville.”
Delfino said though it’s happening at a much smaller scale, the current hydrologic system Florida employs already has the effect of formerly-wastewater making it into our drinking supply, if just more diluted.
Partially treated water is already approved to use for irrigation. After it’s spread across lawns, farms, golf courses and other fields, it’s filtered into the ground and sometimes released into wetlands and water bodies. From there it makes it back into our acquirer and is piped through a water treatment plant before it reaches your tap.
