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To meet the treatment requirements for Cryptosporidium, the Portland City Council chose water filtration as the best option for the Bull Run water source. This decision is a key aspect of the compliance agreement between the Portland Water Bureau (PWB) and drinking water regulators to meet these requirements. Building a filtration plant of this size takes about a decade and treatment must be in place by September 30, 2027. Steps include planning, decision making, permitting, design and construction. The Portland Water Bureau has already begun work on these initial steps.

Benefits of Bull Run Filtration

• Removes organisms from the water, making our water safer. Filtration removes Cryptosporidium and other organisms, improving the safety of our water supply.
• May reduce the amount of chlorine for disinfection and disinfection byproducts. By removing pathogens, filtration may allow us to use less chlorine disinfection in the future. Chlorine kills pathogens, but also reacts with organic material in the water to produce substances called disinfection by-products that have known health effects. Using less chlorine and removing more organic material may result in less by-products.
• Improves year-round availability of Bull Run water. Without filtration, the Bull Run Watershed cannot be used when there is elevated turbidity, or sediment, in the water. This can happen during heavy storms or could result from a fire in the watershed. Filtration is used to remove sediments, allowing greater use of the Bull Run, depending on the severity of the sediment load in the water.
• Provides consistent, high-quality drinking water. Filtration can reduce some of the common causes of taste, odor and color issues that occasionally occur in Portland’s system, such as the ability to remove algae that can affect taste.
• Future investment. Filtration can potentially address future regulations and emerging contaminants that other Cryptosporidium treatment technologies would not likely address.