How is my water disinfected?

TVWD provides water from two high quality primary sources, the Joint Water Commission (JWC) and Portland's Bull Run Watershed. These sources are disinfected in two slightly different ways: JWC uses free chlorine and Portland uses chloramines, which is chlorine with a small amount of ammonia added. Both methods have been approved by the Environmental Protection Agency (EPA) for disinfecting drinking water.

How much chlorine is in my water?

Both of our source water providers carefully monitor the amount of disinfectant added to water as it leaves their treatment plants. Plant operators strictly follow the EPA’s maximum allowable levels in order to protect public health.

Disinfectant residual levels (a measure of how much chlorine is in the water) are monitored 24/7 at all TVWD entry points and over a dozen locations throughout TVWD’s system. Residual readings are also collected from various sample stations around the district hundreds of times each month to confirm your water is safe to drink.

Category: Water Disinfection
What if my water smells like chlorine?

Some people are more sensitive to tastes and odors than others and water disinfected with chlorine or chloramines can be noticeable. Occasional fluctuations in taste or smell do not necessarily indicate an increase or decrease in the disinfectant. It is more likely due to a change in water temperature (especially with warmer weather) or older water age, indicating that the chlorine is dissipating in time.

Blending of our source waters can also cause the water to smell like chlorine. This generally subsides on its own and is no cause for alarm, your water is completely safe to drink.

Category: Water Disinfection
What is water "blending?"

When water from JWC mixes, referred to as blending, with Bull Run water at a ratio close to 50:50, secondary chloramines can be formed. While the water may sometimes seem less palatable, there is no increase in the overall disinfectant level. These reactions can occur more frequently during the summer months when water temperatures are higher. Again, this reaction is purely aesthetic, and the water is safe to drink.

Category: Water Disinfection
Why is water disinfected?

Water is disinfected to protect public health. Chlorine has been added to drinking water in small amounts since the early 1900s to destroy disease-causing pathogens.

Prior to the widespread use of disinfectants, many people became ill or died because of contaminated water. Disinfection kills or inactivates bacteria, viruses, and other potentially harmful organisms in drinking water.

Category: Water Disinfection
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