In-Home Water Filtration Systems for PFAS Reduction

In-Home Water Filtration Systems

Drinking water pouring into a glass.Per- and polyfluoroalkyl substances (PFAS), also known as perfluorinated chemicals (PFCs), are a large group of more than 3000 man-made fluorinated organic chemicals that have been used since the 1950s in firefighting foams, oil and water repellent products, and surfactants. PFAS can be released to the environment by manufacture and use of items that have PFAS in them. PFAS in the environment may enter surface water, groundwater, and drinking water wells. Some wells may have PFAS levels, or amounts, that are high enough to cause concern for human health. For these residents, in-home water filtration systems are recommended to lower the levels of the PFAS in their drinking water.

The U.S. Environmental Protection Agency (U.S. EPA) has set a lifetime health advisory (LTHA) level for two PFAS, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), in drinking water. An LTHA is set to protect human health. To date, the EPA has not set LTHAs for the other PFAS chemicals.

The LTHA level for PFOA and PFOS is 70 parts per trillion (ppt), either singularly or combined when both PFOA and PFOS are found in drinking water. PFOA and PFOS levels below the LTHA are not expected to harm human health. Some filtration systems that lower the amounts of PFOA and PFOS below the LTHA have been certified. However, no systems have been certified for lowering all PFAS.

Certified Filtration Systems

The best way to know how effective your filter is to make sure that it is tested by an independent third party. The packaging for the filter will typically contain this information. This information can also usually be found on the manufacturer’s web page. Also make sure that the filter has been tested using a standardized methodology. Up until recently, the protocol that has been widely accepted has been NSF Standard P473. That standard was recently retired (March 2019) and has been replaced by American National Standard 53 from the American National Standards Institute (ANSI). Using an independent party to test a filter using a standardize protocol helps ensure that the filter has been tested in a uniform manner.

Non-Certified Filtration Systems

There may be other filters that lower PFAS. However, without the NSF P473 certification, it can be difficult to know which filters effectively reduce PFAS and which do not.

In 2007, the Minnesota Department of Health hired Water Science & Marketing, LLC and the Water Quality Association to determine if water filtration systems could lower PFAS in water. At that time, there was no NSF standard for reducing PFAS. Fourteen filters were tested, and eleven of these were shown to sufficiently reduce the amount of PFAS in water. Four of these filters were activated carbon devices and seven were reverse osmosis devices. None of the devices were, or are currently, certified for PFAS removal. It is important to note that the Minnesota Department of Health does not certify water filters.

Here is more information about the study.

Types of Filtration Systems

Both granular activated carbon (GAC) and reverse osmosis (RO) filters can reduce PFAS substances. Both systems provide less water flow than a standard water faucet.

A GAC system:

  • reduces the amounts of PFAS and some other contaminants in drinking water.
  • has a carbon filtration cartridge which captures the contaminants.
  • provides more water flow than an RO system.
  • has cartridges that are rated to treat more gallons of water than those in an RO system and are less expensive to replace.
  • are often easier to install than RO systems.
  • does not remove minerals from water.

An RO system:

  • reduces the levels of more contaminants in water, including arsenic and nitrates, than a GAC system.
  • typically consists of a sediment filter, carbon filters, and an RO system membrane. RO systems force water through the membrane under pressure, leaving the contaminants at the membrane.
  • provides less water flow than a GAC system.
  • uses approximately three times as much water as it treats, and discharges the untreated water to the sewer or septic system.
  • removes minerals from water. Some systems include remineralizers.
  • requires more frequent changes of the filtration cartridge and the RO membrane.
  • is more costly.

Maintenance

For any filtration system to be effective, it must be maintained. Follow the manufacturer’s instructions, and change the cartridges as often as recommended. Most systems include an indicator to notify you when the cartridges or the RO membrane should be replaced.

Cartridge Disposal

The cartridges may be disposed of in household trash. They are not considered hazardous waste.

Local Health Department Contact Information

If you have been notified that PFAS were found in your drinking water well sample, alternate water or a filtration system may be available to you. For more information, contact your local health department