Flint, Mich.’s water woes suggest this might be a good time to take a closer look at something we very much take for granted. Ten percent of the world’s population lives without access to water that is safe for drinking and bathing. That’s twice the population of the United States. Yet virtually everywhere in America you can turn a tap and out flows abundant potable water that costs next to nothing. Let’s go microscopic and take a fantastic voyage through one of our local systems that delivers the resource that is our most immediate need after oxygen.
We begin at the end of the line, a faucet somewhere in Knoxville supplied by KUB. About a quarter-million people receive that water at a cost of about one-half cent per gallon. After we squeeze through the faucet valve we find ourselves in a pipe that is copper or PEX (cross-linked polyethylene) if installed in this century, PVC if installed in the late 20th century, or galvanized iron if older than about 1970. Lead water pipes were banned nationwide in 1988.
Once we’ve passed through the water meter we have to travel some of the 1,400 miles of distribution pipes back to the treatment plant. Older parts of that distribution system, about 42 percent of the total, are galvanized, cast iron, and cement. Newer pipes that comprise about 58 percent of the distribution system are plastic or ductile iron. According to KUB no lead pipes remain in the distribution system upstream of the meters. As part of its Century II long-range program to improve and maintain utilities, KUB replaces 1 percent of the distribution system each year with newer materials.
Along our journey we might go through pump stations and storage tanks that ensure 24 hours worth of stored water in the unlikely case of overall system shut down. When we finally arrive at the treatment plant we encounter the final stages of treatment that include chlorination, fluoridation, and addition of a corrosion inhibitor. Chlorination kills any pathogens that might have slipped through the treatment process, and it keeps on killing any pathogens that might be encountered along the way to the tap. If your tap is close to the treatment plant you might notice more chlorine odor in the water, because chlorine dissipates quickly over time, and a certain amount must be in the water at the farthest point in the distribution system to protect those customers.
Fluoride is added to the water to prevent tooth decay, a practice that began in the United States in 1945. Fluoridation has always been controversial with some, but Knoxvillians voted in 1972 to have fluoride added to their water.
Tennessee requires the addition of corrosion inhibitors to public water supplies. Corrosion can cause metals to build up in the water, and that seems to be what happened in Flint. KUB uses the corrosion inhibitor zinc orthophosphate.
As we work our way backwards through the treatment process, we encounter a filter made up of 12 inches of sand and 20 inches of anthracite. The filter catches any particulates that didn’t settle out in the clarifier, a tank the water spends some time in after having coagulants added to capture suspended solids and other contaminants in the intake water. We’ve had another little blast of chlorine between the filter and clarifier, and yet another dose where the intake water enters the clarifier.
As we continue back toward the Tennessee River, we have to slip through the screen that keeps fish, insects, and debris from coming in with the 34 million gallons of water pumped from the river every day. That intake water is monitored continuously for turbidity (cloudiness), algae, dissolved organic chemicals, pH, and temperature.
If we continue on up the Tennessee River and either of its major tributaries, the Holston and French Broad Rivers, we would see relatively little industry for a long ways. We might also notice more sustainable agricultural practices that add less mud, pathogens, and toxic chemicals than in years past. The quality of the source water in the river is an important part of why we can feel good about our water supply.
What we might not notice from our microscopic vantage point is that our treatment plant off Riverside Drive is one of the most beautiful, ornate buildings left in Knoxville. Built in 1927, the Mark B. Whitaker Water Treatment Plant’s elegant windows, marble floors, and other architectural features were meant to be enjoyed by the public. Sadly, the events of Sept. 11, 2001 heightened concerns for sabotage of public water supplies, especially in urban areas where many people would be affected, so access to the treatment plant is now very limited.
A lot of testing is done to verify the safety of our water. KUB has its own in-house, state-certified laboratory so it can do more testing for more parameters than required. In fact, the annual water quality report for 2015 states that KUB performs more than 100,000 tests annually and checks for over 150 contaminants. Any customer with concerns about their water quality can contact KUB to have their water tested.
You might still be one of those people who prefer to drink bottled water for a variety of reasons. But it’s comforting to know that the safety of our water supply is one less thing to worry about. It’s also a reminder of why it is so important for everyone to protect watersheds. The people and communities who draw water from the Tennessee River downstream of Knoxville deserve the same safe, affordable water supply we enjoy for an average of $22.45/month per household.
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