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Home Filters

A reverse osmosis (RO) water filtration system

Home Filters

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 drinking water wells may have PFAS in 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. In  May 2016, the U.S. Environmental Protection Agency (USEPA) set a lifetime health advisory (LHA) level for two PFAS, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), in drinking water. These are the chemicals that are used in the certification for filters. Because of this, filters are certified to reduce levels in water to below 70 parts per trillion (ppt) for PFOA and PFOS. Currently filters are not certified to reduce other PFAS.  

Get assistance in understanding your drinking water results

Call the Michigan Department of Health and Human Services (MDHHS) at 1-800-648-6942.  The answer can be more than comparing the amount in your water to a drinking water amount intended to protect everyone. MDHHS uses Public Health Drinking Water Screening Levels for PFAS to help citizen’s making personal choices about their drinking water sources. These are shown below.

MDHHS Screening Levels - one of multiple factors for developing health recommendations for drinking water.

  • PFOS: 8 ppt
  • PFOA: 9 ppt
  • PFHxS: 84 ppt
  • PFNA: 9 ppt
  • PFBS: 1,000 ppt

Certified Filtration Systems

The best way to know your filter is effective 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. In the past, the protocol that was widely accepted was the NSF Standard P473. This standard has been retired and replaced by the NSF International/American National Standards Institute (NSF/ANSI) Standard 53 for PFOA and PFOS reduction. For reverse osmosis filtration systems, there is a different standard; the NSF/ANSI Standard 58 for PFOA and PFOS reduction. Using an independent party to test a filter using a standardize protocol helps ensure that the filter has been tested in a uniform manner.

Learn more about Certified PFAS-Reducing Filters

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.

Learn more information about the Minnesota filtration 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.


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.