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How is my water disinfected?

The safety and quality of your drinking water is our top priority at TVWD. We source water from two primary suppliers: the Joint Water Commission (JWC) and Portland Water Bureau. Each employs distinct disinfection methods to eliminate harmful pathogens:

  • Joint Water Commission (JWC): Utilizes free chlorine, a widely used disinfectant that effectively kills bacteria and viruses.
  • Portland Water Bureau: Employs chloramines, a combination of chlorine and a small amount of ammonia, to maintain longer-lasting disinfection throughout the distribution system.

Both disinfection methods are approved by the Environmental Protection Agency (EPA) and are carefully monitored to ensure compliance with federal and state drinking water standards.

Monitoring Disinfectant Levels

Our source water providers meticulously control the amount of disinfectant added at their treatment plants, adhering strictly to EPA guidelines to protect public health. TVWD continuously monitors disinfectant residual levels—a measure of chlorine concentration—24/7 at locations throughout our system. Additionally, we collect hundreds of samples each month from designated water quality sample station sites across the district to confirm your water remains safe to drink.

Addressing Chlorine Taste and Odor

Some individuals may detect a chlorine taste or odor in their water. Such fluctuations are typically due to changes in water temperature, seasonal variations, or the blending of different water sources. These sensory changes are usually temporary and do not indicate an increase in disinfectant levels. Rest assured, your water remains safe to consume.

Understanding Water Source Blending

When water from JWC and Portland Water Bureau blends together, especially at a 50:50 ratio, secondary chloramines can form, occasionally affecting taste. This is more common during warmer months when water temperatures are higher. Despite any changes in taste, there is no increase in disinfectant levels, and the water continues to meet all safety standards.

For more detailed information on water disinfection and quality, please refer to our Annual Water Quality Report.

If you have specific concerns or questions about your water, our Water Quality FAQs provide additional insights and answers.

Your health and safety are paramount to us, and we are committed to delivering water that meets the highest quality standards.

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.

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.

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.

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.

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