Product Sector Guidance: Water Filtration

close up view of someone filling a glass up from the sink

Choosing the Right Water Filtration System

Understanding water filtration systems and processes

These charts show some common types of water filtration systems and processes.  To learn if there is lead in your water supply you can purchase a water testing kit from Healthy Babies, Bright Futures. To test your water for various chemicals and bacteria, contact your local health department or follow the EPA’s home water testing guide.

Filtration Technology

Filtration Process

Type of System



Activated Carbon and Granulated Activated Carbon

Contaminants are removed through adsorption, where contaminants are attracted to the surface of the activated carbon and held to it

Pitcher, Faucet, Counter, Under-Sink, Whole House

Removes or reduces lead and arsenic; improves taste and odor of water; low upfront cost and no installation cost; portable

Price and installation costs for systems go up with size; smaller systems need more filter changes

Reverse Osmosis 

Semipermeable membrane that blocks particles larger than water molecules

Counter, Under-Sink, Whole House

Removes most unwanted contaminants including lead, arsenic and perchlorates

The filtration process wastes water; removes good minerals along with contaminants; cost of system goes up with size, filter quality


This filter process heats water to vaporize it and then condenses the steam back into water

Counter, Floor

Removes chemicals that have higher boiling points than water - lead, arsenic, heavy metals, fluorides and bacteria

Energy inefficient; systems can be large and expensive; removes good minerals along with contaminants  

Ultraviolet (UV)

Uses ultraviolet light to kill bacteria and other microorganisms

Whole House, Portable

Does not use heat or chemicals to remove contaminants; low maintenance

Cannot remove chemical contaminants and works best in addition to other filtration; sensitive to discoloration in water 

Choosing a Water Filter

Once you’ve decided on the type of water filtration system and the process you need to protect your family from contaminants in the water supply, knowing if a product is certified also is important. If a product carries a certification, it means that a third-party tester has verified that it screens for the chemicals and contaminants it claims to filter.

The two certification bodies are NSF International (NSF) and the Water Quality Association (WQA). The state of California also maintains a list of water filtration systems that have been certified to screen arsenic.