Federal drinking water regulations require us to treat our water for Cryptosporidium. Cryptosporidium is a disease-causing microorganism. To comply, we’re building a filtration facility to treat water from the Bull Run Watershed. (The Bull Run is Portland’s primary drinking water source.) We are working to complete the filtration facility by September 30, 2027.
In 2017, the Portland City Council chose filtration over other treatment options. Filtration will do much more than treat our water for Cryptosporidium. It will ensure our drinking water stays safe and abundant for generations to come.
When complete, the Bull Run filtration facility and new pipelines will:
- Remove microorganisms like Cryptosporidium from our drinking water
- Remove sediment (dirt) and organic material (bits of plants) from our drinking water
- Reduce harmful disinfection byproducts
- Likely further reduce lead levels at customer taps
- Prepare our water system for earthquakes, wildfires, landslides, flooding, and other natural disasters
Why the City selected filtration
In 2017, we started detecting low levels of Cryptosporidium in Bull Run water. This prompted the Environmental Protection Agency (EPA) and the Oregon Health Authority (OHA) to require us to treat our water for Cryptosporidium.
City Council considered two options for meeting this requirement: filtration and ultraviolet (UV) treatment.
Both methods would treat our water for Cryptosporidium. UV treatment provides no other benefits. Filtration provides many benefits and addresses real risks to our drinking water system.
The table below compares our current water treatment, UV treatment, and filtration.
| Benefit | Current water treatment | Ultraviolet (UV) treatment | Filtration |
|---|---|---|---|
| Meets Cryptosporidium treatment requirements | No | Yes – inactivates Cryptosporidium | Yes – removes Cryptosporidium |
| Removes sediment (dirt) and organic material (bits of plants) | No | No | Yes |
| Prepares our water system for wildfires, landslides, and other natural disasters | No | No | Yes |
| Reduces cancer-causing disinfection byproducts | No | No | Yes |
| Reduces lead levels at customer taps | Yes – current corrosion control treatment has significantly lowered lead levels | No impact | Yes – testing indicates filtration plus corrosion control treatment will likely further reduce lead levels |
| Has capacity to address future water quality regulations | No | No | Yes |
In 2017, City Council unanimously chose filtration because of its many additional benefits. Soon after, we signed a bilateral compliance agreement with the Oregon Health Authority. That binding agreement requires us to have filtration online by September 30, 2027.
Protecting public health and improving water quality
Clean water is the foundation of public health. Everyone deserves access to safe drinking water, especially our most vulnerable community members.
Filtration is a common drinking water treatment method in the United States. Almost all large surface water systems use filtration to treat their drinking water. Filtration systems ensure excellent water quality by providing multiple layers of protection. These proven treatment methods will make our water even safer.
Filtration will help protect from disease-causing organisms like Cryptosporidium
Currently, we treat our drinking water using chlorine and ammonia. This disinfects our water against almost all microorganisms that could make people sick. However, these treatment methods do not work on Cryptosporidium. Filtration will remove microorganisms, including Cryptosporidium, from our water.
Cryptosporidium is a disease-causing microorganism. In 2017, we detected small amounts of it in Bull Run water. Since then, we have continued to detect low levels of Cryptosporidium, mostly during the rainy season. Exposure to Cryptosporidium can cause cryptosporidiosis, a serious illness. The current levels in our water are safe for most people. But those with severely weakened immune systems are at risk for more serious disease.
Filtration will remove Cryptosporidium from our water. This will further protect our most vulnerable community members from serious disease.
Filtration will reduce disinfection byproducts
Disinfection byproducts form when chlorine interacts with naturally occurring organic material in the water. High levels of disinfection byproducts can cause health problems in people, including cancer.
The EPA requires disinfection byproducts to be below a certain level. We regularly test our water for them and report our results in our annual Water Quality Report. Currently, they are present in our water at levels below the EPA limits.
The filtration facility will remove organic material from our water. This will reduce disinfection byproducts and make our water even safer.
Filtration will likely further reduce lead levels at the tap
In Portland, the main source of lead in water is corrosion (wearing away) of home plumbing. We treat our water to make it less corrosive and reduce lead levels at the tap.
Our current corrosion treatment happens at our Improved Corrosion Control Treatment (ICCT) facility. Completed in 2022, ICCT has significantly reduced lead levels at customer taps!
Filtration will build on the success of this investment. We will continue corrosion control treatment at the new filtration facility. Our testing shows that filtration combined with corrosion control treatment may reduce lead levels even more.
Filtration will make it easier to address future water quality risks and regulations
Filtration is a robust water treatment method that can address many possible contaminants. New risks to drinking water safety can emerge over time. We considered those potential risks when designing the new facility. Our filtration facility will make it easier and more cost-effective to address new risks or regulations in the future.
For example, the Bull Run Watershed is currently at low risk for harmful algal blooms. However, climate change could increase the risk in the future. Our current water treatment can’t address algal toxins. With the filtration facility, we’ll be able to adapt our treatment strategies to handle algal toxins if needed. One option would be to ozone treatment, which destroys algal toxins.
The flexibility of filtration will allow us to more efficiently adapt to water quality changes in the future.
Making our water system more resilient and prepared for emergencies
Resilience is the ability to withstand challenges, adapt to changes, and recover from difficulties. A resilient water system can handle emergency events with minimal service interruptions. Following a major emergency, Portland will need access to clean and safe water to recover. That’s why preparing our water system for emergencies is one of our top priorities.
Our water system faces real risks. A large earthquake could happen at any moment. Climate change is increasing the risks of fires and extreme weather. Filtration is a major investment in preparing our water system for these and other risks.
Filtration will help ensure clean and safe water is available sooner after an earthquake
A large Cascadia Subduction Zone earthquake (“the Big One”) could happen at any time. An earthquake of that size would badly damage much of our current infrastructure. That includes our current water treatment facilities.
The new filtration facility and pipelines follow modern seismic standards. That means they will be able to better withstand future earthquakes. The filtration facility will protect essential parts of our water system and help us get safe drinking water flowing sooner in the aftermath.
The filtration project will replace sections of aging, vulnerable pipes
This project includes new pipes to connect the new facility to our water system.
The new pipes will replace some segments of older conduits in the area. Conduits are very large pipes that move water from the Bull Run to treatment facilities and then to town. The conduits we will be replacing are more than a hundred years old.
Some of the existing conduits in the area are at the end of their useful lives and vulnerable to damage. If these pipes break or get damaged, me might not be able to deliver enough water to Portland. Replacing these aging pipes will make our water system more reliable. In addition, the new pipes will be able to better withstand an earthquake.
Filtration will allow us to serve Bull Run water after a major storm, landslide, or other natural disaster
In the Bull Run Watershed, organic material can flow into our water reservoirs. Organic material includes things like sediment (or dirt) and decomposing leaves. Normally, this organic material is present at a very low level and doesn’t affect water quality.
Heavy rains, storms, or landslides can cause a lot of sediment to enter the reservoirs all at once. This leads to increased turbidity (how cloudy the water is). High turbidity can interfere with our water treatment process. When turbidity levels are too high, we are required to stop serving Bull Run water.
Currently, when turbidity is too high in the Bull Run, we use our groundwater system. But the well field has limited capacity, so we can’t use it as our only water source for long periods of time.
Climate change will likely increase the frequency and severity of extreme weather. We need to prepare to handle more frequent turbidity events in the Bull Run.
The filtration facility will be able to remove sediment and organic material from our water. This will allow us to treat and serve Bull Run water during turbidity events in the watershed.
Filtration will better prepare us to recover after a fire in the Bull Run Watershed
In August 2023, a lightning strike sparked a wildfire in the Bull Run Watershed. The Camp Creek Fire burned 2,055 acres near our water source. Fortunately, the fire hasn’t caused any water quality issues to date. This fire didn’t affect our ability to safely serve Bull Run water—but it could have.
Like a storm or landslide, a wildfire could cause a major turbidity event in the Bull Run. After a fire, rains could wash large amounts of dirt, plant debris, and ash into our reservoirs. Climate change is increasing the risks of more frequent, more severe wildfires. That in turn increases the risks of a fire in the Bull Run.
The filtration facility will be able to address the impacts of a fire by filtering out sediment and ash. Filtration prepares us to keep serving safe water, even after a wildfire.