TVWD receives water from two primary sources, each offering water with distinct mineral levels and hardness characteristics. Seasonal changes and demand can result in customers receiving water from a single source or a blend of both. This means the mineral content and hardness of your water may fluctuate throughout the year.
Are TVWD's Water Sources Hard or Soft?
The hardness of water in TVWD's system varies depending on the source and time of year:
- Portland Water Bureau: This source typically has a hardness of 6–11 parts per million (ppm) or less than 1 grain per gallon, which is considered soft water.
- Joint Water Commission (JWC): This source has a hardness of approximately 34 ppm or 2 grains per gallon, which is also considered soft.
During the summer, the Portland Water Bureau's supply may be supplemented with groundwater from the Columbia South Shore Well Field to meet seasonal demand. When blended, this can increase the water’s hardness. Additionally, TVWD sometimes incorporates Aquifer Storage and Recovery (ASR) water during warmer months, which may also contribute to a slight increase in hardness.
Depending on your location within TVWD, you may receive water from all sources in varying proportions. Overall, TVWD's water is generally on the softer end of the hardness scale.
pH Levels and Water Chemistry
Water pH, a measure of acidity or alkalinity, is another key component of water chemistry that TVWD carefully monitors:
- Portland Water Bureau: Water from this source is adjusted to a target pH of 8.8.
- Joint Water Commission (JWC): Water leaving the treatment plant has a target pH of 7.7.
TVWD continuously monitors pH levels using multiple online analyzers and collects hundreds of routine samples throughout the system each month. The pH readings typically range from 7.7 to 8.8, ensuring optimal water chemistry for corrosion control and water quality. Note that home test kits used to measure pH, especially those relying on color charts, may not provide accurate results.
If you’re using a home test kit to measure pH, keep in mind that some kits, especially those relying on color charts, may not provide accurate results. The Oregon Health Authority requires TVWD’s water to consistently test above 7.4 to maintain optimal corrosion control across the system.
Learn more in our Annual Water Quality Report.
Where Can I Learn More About Source Water Chemistry and Minerals?
For detailed information about the water chemistry and mineral content of TVWD's source water, the following reports are available:
These resources offer additional information about the characteristics of the water you receive, including minerals, pH, and other important factors that influence water chemistry.
For more details about TVWD's system operations and water management, visit our news feed.