Testing Our Tap Water

By: Angela Chen Email
By: Angela Chen Email

RENO, NV - We depend on it to survive, but do you know exactly how your water gets from Lake Tahoe to your tap?

For the Reno-Sparks area, the Truckee Meadows Water Authority or "TMWA" supplies your water.

The company received an award from the Partnership for Safe Water for being in the top 2% of the nation for having the best water.

The water is reportedly so clean that TMWA officials claim the tap water is just as good as bottled water.

KOLO 8 News Now wanted to see if that claim was true, so we toured TMWA's treatment plant to see the six stages of how raw water from the Truckee River becomes safe to drink.

As the snow melts and flows down into Lake Tahoe, it feeds into the Truckee River, part of which flows into the treatment plant.

Stage One is Pre-Settling, which filters out all the large objects, like rocks and twigs.

"We're very blessed with such a good water system upstream. You don't have a lot of industry feeding into the water system," said Will Raymond, Water Operations Supervisor for TMWA. "We don't have a lot of pollution from storm drains. This is some of the best water we're going to get out of the Truckee River."

But even though the water seems clear, parasitic micro-organisms live in the river, and experts say you should never drink straight from it. TMWA officials say they know how dirty or clean water is by using a turbidimeter.

"How a turbidimenter works is it gauges how clean or dirty the water is," said Raymond.

At the start of KOLO's tour, the raw water tested at about a 1.67 NTU, nephelometric turbidity unit. The government requires the water to be under .3 NTU before it can stream out to consumers.

After all the large objects are filtered out comes Stage Two: Rapid Mix.
"Right now, we're going to walk down into the rapid mix section of the water treatment process," said Raymond. "This is where we add the polyaluminum chloride, the very well known water treatment chemical. It's very safe, and it's certified by the NSF for water treatment chemicals."

During Stage Two, polyaluminum chloride helps dirt particles clump together so the particles are easier to filter out. They call these clumps "floc" which leads to Stage Three: Flocculation.

"The whole point of flocculation is to use the chemical that was intermixed in the rapid mix to start to get a lot of these really small particles to bind together," said Raymond. "They start getting a little bit heavier, a little bit larger, as it goes through this over under process of flocculation."

Stage Four is Sedimentation.

"Now you have the floc that came over from flocculation, and the only way to get into these troughs is to work its way against gravity through these plate settlers which is why the water is super clean after the plate settlers," said Raymond. "You can see all the floc before it's gone through."

Stages Five and Six are Filtration and Disinfection, the final stages of the water treatment. At the end of the tour, Raymond showed us the turbidimeter for the treated water. The result was a 0.02 NTU level.

"There is an assumption that bottled water is safer or cleaner or something like that because you're buying it as a product at the grocery store," said Raymond. "Tap water that comes out of your faucet is regulated by the EPA, and that's definitely more rigorously tested, and we're held to a higher standard than the FDA holds bottled water."

As for the claim that tap water is just as pure as bottled water?

We put it to the test with a turbidimeter -- a machine that analyzes how clean the water is.

First, we looked at how Arrowhead, Dasani, and Smart Water did.

Each tested around 0.06 NTU.

Then we examined the tap water, and found that it tested 0.067 NTU.


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