Various types of water treatment devices are certified for household use. These devices can remove a broad range of contaminants from water and minimize taste and odor issues.
DC Water recommends point-of-use filters, such as faucet mounts and pitcher-style filters. Faucet mounts should also have protection against microbial growth noted (not certified) on the package because they are not refrigerated and therefore more optimal for microbial growth. Pitcher filters should be stored in the refrigerator, which in addition to providing the cold temperature also does not allow sunlight exposure which promotes algae growth.
Filter Certification
Filters should be certified to remove the contaminant you want to remove. The certification number and type of contaminant must be listed on the package.
See EPA’s guidance on how to identify certifications
Water Filter Maintenance
First Use: You must follow the manufacturer’s instructions for installing and flushing the filter before drinking or cooking with the filtered water.
It is important to routinely replace filter cartridges according to the manufacturer's instructions. Over time, a filter can accumulate metals and bacteria.
Water filters and cartridges can vary in their longevity (length of use) and replacement costs.
Filters For Lead Removal
Filters must be certified to meet NSF 53 for lead reduction and NSF 42 for particulate reduction.
If you have a lead source or do not know if you have a lead source, DC Water recommends that you filter your water before drinking and cooking until all sources of lead have been removed. This includes water used for making infant formula, beverages, and ice.
Filters For Per- and Polyfluoroalkyl Substances (PFAS) Removal
EPA’s new standard for PFAS is very low and the current certification standards for PFAS filters (as of April 2024) do not yet indicate that a filter will remove PFAS down to the levels EPA has now set for a drinking water standard. EPA is working with standard-setting bodies to update their filter certifications to match EPA’s new requirements. In the meantime, the currently available filters can still reduce levels of PFAS in your water, which is an effective way to limit your exposure.
Types of filters that are can be effective at reducing PFAS include:
- Charcoal (Granular Activated Carbon or GAC): These filters use carbon to trap chemicals as water passes through them.
- Reverse Osmosis (RO) Systems: Reverse osmosis is a process that forces water through an extremely thin barrier that separates chemicals from the water.
- Ion Exchange Resins: Resins are tiny beads that act like powerful magnets that attract and hold the contaminated materials from passing through the water system.
Filters For Microorganism Removal and Inactivation
Our drinking water is effectively treated for pathogens at the water treatment plants through filtration and disinfection with chlorine and chloramine. However, people with health conditions, especially those who are immunocompromised, may want to treat their water further.
The Center for Disease Control (CDC) has additional information about home water systems
Applicable certifications are:
- NSF 53 for cysts reduction
- NSF 55 Ultraviolet light
- NSF 58 for Reverse Osmosis
- NSF P231 for Microbiological water purifiers
