Resource
On this page
Water Treatment Has a History of Saving Lives
- One of the world’s greatest public health accomplishments has been using chlorine to kill disease-causing microorganisms and safeguard drinking water supplies.
- Today, water treatment continues to save millions of people — advancing the health of communities worldwide.
- When Portland began adding chlorine disinfectant to drinking water in 1929, we nearly eliminated waterborne disease outbreaks.
- Ammonia was added in 1957 to make the chlorine last longer in our water system.
- Since 1997, Portland has been reducing the danger of lead leaching from home and building plumbing by adding sodium hydroxide to make our water less corrosive.
Improved Corrosion Control Treatment Will Further Reduce Lead Exposure
- In 2022, the Improved Corrosion Control Treatment project will add sodium carbonate and carbon dioxide to increase pH and alkalinity making our water even less corrosive to lead and other metals found in home and building plumbing.
- Improved treatment will rely on naturally occurring substances to treat our water: sodium carbonate and carbon dioxide.
- Sodium and carbonates are naturally present in drinking water because they are present in many natural soils, sources of surface water and groundwater, and plants.
- The amount of sodium carbonate added to drinking water to adjust pH and alkalinity for corrosion control is between 22 ppm and 35 ppm. These additions are very small compared to naturally occurring sodium and carbonate found in food, beverages, and natural waters, as well as compared to quantities added to foods and beverages for special effects.
- For comparison, carbonated beverages contain between 2,700 and 10,000 ppm carbonate ion. Soft drinks contain between 80 and 250 ppm of sodium.
Filtration Will Remove Cryptosporidium and Other Contaminants
- The new filtration facility will be in operation by September 30, 2027, to help us meet national drinking water standards.
- Drinking water treatment for Cryptosporidium, a potentially disease-causing microorganism, is regulated by the Long-Term 2 Enhanced Surface Water Treatment Rule. This rule requires systems that use an unfiltered surface water source, such as the Bull Run supply, to treat for Cryptosporidium.
- Once online, the filtration facility will remove sediment, organic material, and other potential contaminants from our water, providing consistent high-quality drinking water and making our water system more reliable.
How Bull Run Water Will Be Treated
- Clean and safe water starts with the highly protected Bull Run Watershed.
- Organics in our water will be broken down by ozone, which provides a barrier against algal toxins and other contaminants.
- Silt and small particles will slowly settle out and be removed in sedimentation basins.
- Remaining silt or particles will be trapped and removed by filtration.
- Chlorine will protect filtered water from bacteria and viruses.
- Ammonia stabilizes the chlorine for longer-lasting protection.
- Continued treatment to reduce the corrosion of lead from household and building plumbing.
Treatment Processes Meet Rigorous Public Health Safety Standards
- The new filtration facility will use additional safe treatment chemicals to more thoroughly clean our drinking water. Most of these chemicals are used up in the treatment process and do not leave the facility.
- The water treatment process will only use chemicals certified as safe for use in drinking water applications by NSF International. NSF International sets public health standards and certification programs.
- All treatment chemicals currently used and those proposed for future use are commonly and safely used at water treatment facilities nationwide.
- All chemicals added for water treatment will be routinely tested and monitored by trained water professionals to make sure our drinking water meets the highest standards.
- Water treatment chemicals used at the filtration facility will be transported and stored following strict protocols designed to keep workers and the public safe.
Pilot Used to Identify Treatment Best Suited for Bull Run Water Supply
- We are adapting to changes in science, technology, and water quality, and evaluating which treatment processes work best with Bull Run water.
- Water quality engineers are evaluating the effectiveness and efficiency of specific treatment processes and chemicals for our unique water source using a mini-filtration facility called a pilot plant.
- The water treatment chemicals under evaluation are commonly used at water treatment facilities nationwide.
- A panel of independent drinking water treatment and public health experts are advising us to help guide treatment decisions.
- The treatment chemicals we select for use at the future filtration facility will be optimized to reduce operating costs and promote effective treatment.
Treatment Chemicals Will Be Removed During Treatment Process
- Water treatment uses chemicals (coagulants and polymers) to help remove suspended sediment, disease-causing pathogens, and other contaminants.
- These chemicals are almost completely removed during the sedimentation and filtration steps of the treatment process.
- Remaining treatment chemicals, as well as contaminants removed from the water, are then concentrated into a solid with a consistency similar to wet earth that can be used for landfill daily cover or other beneficial use.
- Some chemicals are added and remain in the treated water to make it less corrosive to piping.
- We currently add chlorine and ammonia to our water supply for disinfection and to provide a protective disinfectant residual in our distribution system.
- Water leaving the water filtration facility will continue to have disinfectant and anti-corrosive water chemistry adjustments to protect public health.
The cleaner water produced at the filtration facility will also make chlorine less likely to form disinfection byproducts in the distribution system, enhancing public health protection.
Safety is a Top Priority in Filtration Facility Design and Operation
- Safety of our customers, site neighbors, and staff is of paramount importance and will be an essential part of facility design and operation.
- We are evaluating inherently safer technologies for the filtration facility that minimize risk to the public and facility staff.
- For overall safety reasons, gaseous chlorine will not be used at the filtration facility. We anticipate using liquid sodium hypochlorite, similar to household bleach, for disinfection.
- The facility will meet rigorous state and federal safety standards for chemical storage and transportation.
- Risk management and emergency action plans will be developed for the filtration facility and will follow industry best practices for emergency preparedness.
Bull Run Treatment Projects
We are making two important improvements to our water supply from Bull Run to help keep our water safe and abundant for generations to come. Improved Corrosion Control Treatment will be in place in 2022 and will further adjust the chemistry of our water, reducing potential levels of lead at the tap. Filtration will be in operation in 2027 and will remove the microorganism Cryptosporidium and other potential contaminants from our water. Both projects are required under state and federal law.