Filtering or treating drinking water at home

In most cases, you do not need to filter Portland's drinking water. We deliver high-quality water that meets or exceeds all state and federal drinking water standards. Some people choose to filter their water due to a taste preference, health condition, or water quality issue specific to their home (such as iron or lead leaching into the water from their home plumbing).

If you choose to use a filter, plan on replacing the filter more frequently than manufacturers' recommendations. Bull Run water is currently unfiltered and has more naturally occurring materials for home filters to remove. Because of this, filters can slow down or clog more quickly than manufacturer estimates. Find more information below in the clogged filter section.

Portland is currently installing a filtration facility and anticipates Bull Run water will be filtered by September, 2029. When the Bull Run filtration facility is complete, we anticipate home filter longevity will improve since the filtration facility will remove Cryptosporidium, sediment, and organic matter.

• Lead leaching into water from household plumbing. While lead is rarely found in our source waters and there are no known lead service lines in Portland's distribution system, lead is in the plumbing of some homes and businesses. Lead in that plumbing can dissolve into drinking water when the water sits in the pipes for several hours. A lead-certified filter will remove lead.
• Taste and odor preference. You might prefer the taste and smell of filtered water, or you may have old iron pipes in your home that affect the taste of your water, and you'd like to filter out that taste.
• Chlorine sensitivity. If you have a chloramine (chlorine + ammonia) sensitivity, you might prefer to filter your drinking water or install a showerhead that removes chloramine.
• Cryptosporidium in the water. We do not currently treat for the microorganism Cryptosporidium.  If you have a compromised immune system, your health care provider might advise you to filter your water to remove Cryptosporidium cysts. Find more information below in the choosing a filter to remove Cryptosporidium section.

Home filtration systems generally use carbon, charcoal, or a blend of filter media to remove contaminants as water flows through the filter. Depending on the type of filter, contaminants either get trapped in the pores of the filter or adhere/absorb to the surface of the filter media. In reverse osmosis (RO) systems, the water is usually treated with a pre-filter, a carbon filter, an RO membrane, and a post-filter.

The first step is to determine what you want the filter or treatment device to do. Do you want it mainly to remove tastes and odors? To remove contaminants, such as lead? Before you buy a filter, you may want to find out if the contaminant is a problem in your home. To determine if your home plumbing contains lead, request a free lead-in-water test kit online. To learn more about Portland's water quality, visit our drinking water test results page.

There's a variety filter styles that include pour-through pitchers and carafes, faucet-mounted filters, countertop and under-sink filters, showerhead filters, and refrigerator filters.

Not all filters work the same. Read the packaging carefully and only purchase a filter certified by NSF/ANSI (National Science Foundation/American National Standards Institute). Here are some standards to look for:

• NSF/ANSI Standard 42 certified filters reduce non-health-related contaminants and change the aesthetics of the water. The contaminants reduced will vary by filter.
• NSF/ANSI Standard 53 certified filters reduce contaminants that are harmful to health. The contaminants reduced will vary by filter.
• NSF/ANSI Standard 58 certified filters reduce a wide variety of contaminants through reverse osmosis treatment systems.
• NSF/ANSI Standard 177 certified showerhead filters reduce free chlorine.

Don't rely on the NSF/ANSI certification alone; make sure the packaging specifically lists the contaminant you wish to reduce. For example, you may find two filters that are both NSF/ANSI 53-certified, but only one of them may be certified for lead reduction.

Choose one of the following types of filters to remove Cryptosporidium:

• Reverse osmosis filters.
• NSF/ANSI 53- or 58-certified filters that also include the language "cyst reduction" or "cyst removal."
• Filters with an "absolute" pore size of 1 micron or smaller. If the package only states "nominal" pore size of 1 micron, then it may not remove all Cryptosporidium.

Follow the manufacturer's recommended filter cartridge replacement schedule. Because filter cartridges collect Cryptosporidium, it's a good idea to have someone who is not immunocompromised change them. It's also a good idea for that person to wear gloves while changing the cartridge. Learn more about Cryptosporidium and home water filtration at the CDC's Filtering Tap Water page.

The NSF/ANSI Standard 177 is for showerheads that reduce free chlorine. Since Portland uses chloramine (chlorine + ammonia) and not free chlorine, filters with the NSF/ANSI standard may not work effectively. Some certified showerheads on the market with granular activated carbon claim to also reduce chloramine. You may have success with vitamin C showerhead filters, but these are not certified. 

Point-of-use filters treat water only where and when you need filtration, such as at your kitchen sink or refrigerator. Point-of-use filters are often more economical, but if you wish to treat water at multiple locations in the home, you will need to buy a filter for each location. Point-of-use filters are a good choice when you want to remove contaminants that originate in your home plumbing (such as lead).

Point-of-entry filters treat all water that enters your home. This will include your kitchen sink and refrigerator, of course, but also your toilet water, bath water, laundry water, and in some cases water at your outside spigots. Point-of-entry filters may be more expensive, and will not address issues in the plumbing that cause problems after the filter (such as lead solder in your household pipes). If you use a point-of-entry filter that removes chlorine and sodium hydroxide, it's important to keep in mind that you are removing the disinfectant and pH adjustment in your tap water. This could lead to bacterial growth and corrosion of home plumbing.

You can buy filters online and at hardware stores, grocery stores, and other retailers.

Replace your filter cartridge according to the manufacturer's guidelines to ensure your filter continues to perform as designed. Filters that are not maintained or replaced according to the manufacturer's schedule may not filter out contaminants and can also harbor bacteria. For example, a filter designed to remove 99 percent of lead can only do so for a specific volume of water. Many filters have a device that indicates when to change the filter.

Certified water filters start around $20, with replacement filters being less expensive than the initial device. Filtration pitchers and faucet-mounted filters generally cost less than filters that are plumbed in below a sink. Reverse osmosis systems are more expensive than carbon filtration systems. When choosing a filter, consider filter replacement costs and only purchase a system that you are willing to maintain.

Many filters will have lower flow as they near the end of their lifespan, indicating that they need to be replaced. There are several factors that can contribute to clogging or a shorter lifespan.

Portland's Bull Run drinking water is unfiltered, so filters may not last as long as they would in a filtered drinking water system. Bull Run source water contains naturally occurring sediments and organic materials and occasionally experiences seasonal increases in algae and zooplankton known to clog filters. These seasonal algae and zooplankton increases can last several weeks but do not pose a health risk.

Filter clogging since mid-May 2026: The Bull Run Watershed reservoirs are seeing increased levels of plankton (algae and zooplankton) that, while not harmful to health, may be resulting in premature filter clogging. We do not have an estimate on when they will start decreasing, but Bull Run reservoir conditions indicate that a decrease should begin within weeks.

Filter lifespans can also be impacted by the naturally occurring material from Bull Run that are always present at the bottom of our water mains. This material can sometimes be stirred up during construction, hydrant use, firefighting, and main breaks, creating a temporary situation where filters have a higher load of material to filter out.

How much water you filter and where you filter could impact filter lifespan. For example, a point-of-entry filter removes material from all water entering a home, including water for toilets, laundry, and showering, and can have a shorter lifespan than a point-of-use filter that is used only to filter water for drinking or cooking.

Lastly, your filter could be impacted by conditions in your home plumbing. For example, if you have older iron pipes, corrosion particulates may cause your filter to clog prematurely. 

If clogging is frequent, contact the Water Quality Line.

The most straightforward alternative is to not filter or treat the water at home, since Portland's water meets or exceeds state and federal standards. However, if you want to manage your home water quality while avoiding the use of home filters, we have a variety of options for you to consider.

If you haven't used the water for several hours, running your water for 30 seconds to 2 minutes will move stale water out of your plumbing and bring in fresh water from the water main in the street. 

If you have lead in your plumbing, running water like this is important to flush the lead out before using the water (do not boil your water to remove lead). Flushing your faucet will also address taste and odor issues created by your plumbing or water changes from older iron pipes, such as taste or color. 

To remove chlorine taste and odor, you can:

• Add slices of lemon, lime, or other citrus fruits to a pitcher of water. The ascorbic acid (vitamin C) will help dechlorinate the water. 
• Boil water and let it cool before using. While this reduces chlorine levels, use caution if you have lead in your plumbing since boiling water could result in higher lead levels. 

Bringing water to a rolling boil for one minute will disable Cryptosporidium cysts (let the water cool before using). However, use caution if you have lead in your plumbing since boiling water could result in higher lead levels.