Darian Hale & Diego Lerma | GNP contributors
When you open the tap on your sink, you’re getting a mix of super-filtered water from the Tar River. Few people may know how that water comes to be and how it makes its way to the multitude of sinks, showers and water fountains all over the city.
The Greenville News Project spent the months of fall tracking the water’s path.
It starts at the Tar River and runs through a complicated system of filters and quality tests. Then it runs through over 700 miles of potable water pipes to meters at homes, schools and businesses. After that, it leaves custody of the publicly owned Greenville Utilities and pours into customers’ pipes.
Starts at the Tar
It is called “surface water,” and it is all Greenville drinks, cooks with and bathes in. Still, Greenville Utilities (GU) has a backup plan. “We have 3 deep wells (groundwater) that can be activated for emergency use,” Chad Flannigan, a GU chemist and lab supervisor, told GNP on its tour of the Water Treatment Plant (WTP).
But it is not a direct route from the river to homes. GU takes the river water through a long and complex process that filters out contamination.
The filtering process starts with bringing the river water into the WTP with specialized screens placed at the bottom of the river. The screens are eight feet long and sit on the riverbed so that boats do not run over them.
The screens have small holes that draw the water into the plant’s raw water station. Rapid mix pumps along with gravity move the water through the cleaning process.
GU mixes aluminum sulfate, referred to as “alum,” into the river water at the beginning of the treatment process. “The alum is negatively charged,” Flannigan said, “and these particles in [the water] are what we want to get out [and they] are positively charged, and so they'll attract each other and start to combine together.”
When the combining happens, small movements that resemble cracks in the water appear.
There are nine stations where the particles combine. They are called “flocculators,” and they basically are holes in the ground where the positive river particles and negative alum particles join up.
The flocculators get their name from the process of removing the joined particles from the water. They form flakes, or “floc,” when they combine.
When the river water leaves the flocculators, it goes into sediment basins, and that is where most of the floc is removed. The WTP has six sediment basins filled with water from the Tar.
The basins have small cone-shaped holes that the water goes through, and they are known as “stilling wells.” They allow for the water’s depth to be measured.
This part of the water-cleaning process usually takes about four hours, but that depends on the flow of the water. The basins have a special instrument known as a “track vac” that cleans the bottom of the basin. The track vav removes any sludge that gets left behind during the treatment process.
To Flannigan, the flocculators and sediment basins are the “work horses” of the water treatment process.
“You have probably 90% of the stuff that's in the water that we don't want in the water when people have it coming out of their taps,” he said. That stuff is “removed in these processes.”
After the water leaves the basins, it runs through 11 deep bed filters and then into the ozone facility. There, GU checks the turbidity of the water before adding any disinfectants to it.
Turbidity is about water clarity. It measures how clear or cloudy water is.
The ozone facility has a distinctive hum to it that is made by the machinery. The facility went online in 2002, and “it gives us an opportunity to just get some disinfectant in the water much earlier than we can,” said Flannigan, raising his voice to be heard over the hum.
The ozone is made by running electricity and oxygen going through specialized equipment. If any ozone is released into the environment, it can have negative effects. That is why there also are devices in the facility that get rid of any excess ozone.
Water flows through “contactors” where the ozone is released into it. After that, the now-cleaned water gets additives, one of which is fluoride.
Now the water that got siphoned out of the Tar River is ready to be distributed throughout Greenville by five main pumps located in the WPT.
From pipe to meter to house
The clean water may not stay that way depending on what kind of pipes run from the Greenville Utilities meter into homes, schools and businesses. GU says that only homes built before the 1930s could have lead pipes or lead solder unless they have been renovated. Both were used until 1985, and lead is a health hazard.
At ECU’s Health Sciences campus, the “water quality is very good … thanks to GUC,” said Kevin Dorsey, the plumber supervisor there. The campus opened in 1980, making it younger than the university’s original campus downtown.
The Health Sciences “buildings are all copper pipes with lead-free solder for the most part,” said Dorsey. When they were built, all the piping came from Greenville Utilities, he said.
Residential water piping can be made from several different materials. Dorsey said that includes include PVC copper and PEX piping.
Threats to clean water
With the drinking, cooking and shower water starting at the Tar, the river’s health is important. Katey Zimmerman, a Tar-Pamlico riverkeeper and leader of Sound Rivers, said stormwater runoff can impact the river’s health.
“In urban areas like Greenville and Washington, when it rains, it picks up all those pollutants like bacteria and nutrients and just washes into the river,” she said.
Urbanization is a river-health risk too. It can lead to the loss of vegetation and agricultural land that are natural filters for water.
Plus, “variability in weather patterns, such as hurricanes and droughts, can lead to extreme river flows, causing flooding and crop losses,” said Michael O’Driscoll, a hydrologist in the Department of Coastal Studies at ECU.
Urban areas with sewer collection systems with aging infrastructure tend to attract pollutants. In rural areas, runoff can threaten water quality because of fertilizers, pesticides and farm waste.
“The Tar-Pamlico River is a nutrient-sensitive waterway, so nutrients like nitrogen and phosphorus are more prominent in the river due to the agricultural land run-off,” said O’Driscoll.
According to the federal Environmental Protection agency, too much nitrogen and phosphorus in the water can be harmful to waterways. It can lead to algae growing more quickly than ecosystems can manage.
Another threat to filtration is the rising sea levels, which can cause saltwater intrusion in areas near the coastlines. “The saltwater from rising sea levels is reaching higher elevations, making it easier to move inland,” said O’Driscoll.
“During [this summer’s] droughts, it came 10 miles to the City of Greenville and it’s possible it could have further,” he said.
As Zimmerman said, “Knowing where the water comes from and the different factors that play a role is important.”
Hale and Lerma produced this story for the Fall 2024 course In-depth Reporting Capstone at the School of Communication, East Carolina University.
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