Technology
How does a water filter work?
A water filter cleans water by passing it through one or more barriers that trap or remove contaminants. Different filters target different things — physical sieves catch particles, carbon absorbs chemicals, and fine membranes block microbes.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how a water filter works.
Step by step
- 1Physical filters act like fine sieves, trapping dirt, sand, and larger particles.
- 2Activated carbon absorbs many chemicals, odors, and bad tastes onto its huge surface area.
- 3Very fine membranes, as in reverse osmosis, block dissolved salts and microbes.
- 4Some filters add UV light or chemicals to kill bacteria and viruses.
- 5Filters must be replaced periodically as they fill up or wear out.
Frequently asked questions
- What does activated carbon remove?
- Its enormous internal surface absorbs many chemicals, chlorine, odors, and tastes — but on its own it doesn't remove dissolved salts or all microbes.
- What is reverse osmosis?
- It forces water through a membrane so fine that it blocks dissolved salts, most contaminants, and microbes, leaving very pure water.
- Do water filters remove bacteria?
- Some do — very fine membranes or a UV stage can remove or kill microbes — but basic carbon or sediment filters mainly target particles and chemicals.