Find your filter.
Five types of water filter, compared honestly: what each one removes, where it goes and what it takes to keep it running.
At a glance
Side by side.
Purity is a relative guide to how broad a range of contaminants a typical system reduces. Always check a product's NSF/ANSI certifications.
| Type | Best for | Typically reduces | Purity | Install | Maintenance |
|---|---|---|---|---|---|
| Reverse osmosis | Drinking & cooking water | Dissolved solids, lead, arsenic, fluoride, nitrates, plus chlorine, taste & odor (with carbon pre/post stages) | Under sink; needs a drain line and dedicated faucet | Pre/post filters every 6–12 months; membrane every 2–3 years | |
| Countertop | Renters, small kitchens | Chlorine, taste & odor; many models also reduce lead and some chemicals (check certifications) | Sits on the counter or attaches to the faucet; no plumbing | Cartridge every 2–6 months | |
| Under counter | Everyday filtered tap water | Chlorine, taste & odor, sediment; multi-stage units add lead and cyst reduction | Under sink, on the cold line; optional separate faucet | Cartridges every 6–12 months | |
| Shower | Skin, hair & chlorine sensitivity | Primarily chlorine (KDF, vitamin C or carbon media) | Screws between the shower arm and head | Cartridge every 3–6 months | |
| Whole house | Protecting the whole home | Sediment, chlorine/chloramine, taste & odor at every tap and appliance | Point of entry on the main line; often professional install | Sediment every 3–6 months; carbon tank or cartridge per rating |
Questions
Good to know.
How do I know what's in my water?
If you're on municipal water, your utility publishes an annual Consumer Confidence Report. On a private well, get a certified lab test. Choose your filter based on what's actually in your water.
What do NSF/ANSI certifications mean?
They're independent standards for what a filter has been tested to reduce. NSF/ANSI 42 covers aesthetic effects like chlorine taste and odor, 53 covers health-related contaminants like lead, 58 covers reverse osmosis systems and 401 covers emerging contaminants.
Does reverse osmosis remove healthy minerals?
Yes, along with the contaminants. Most people get their minerals from food, but if you prefer the taste, a remineralizing post-filter adds calcium and magnesium back.
Can I combine filters?
Yes, and many homes do: a whole-house system for sediment and chlorine, plus reverse osmosis at the kitchen sink for drinking water.
What happens if I don't change my cartridges?
Saturated media stops working and clogged filters can slow your flow. Follow the manufacturer's schedule, and change them sooner if you notice taste, odor or flow changes.
Still deciding?
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