Whole house water filters
A whole house filter treats water where it enters the building, so every tap, shower and appliance gets filtered water. It is the right choice for problems that affect the whole property — chlorine smell, sediment, rust staining, limescale — and the wrong one if you only want better drinking water at the kitchen sink.
For drinking water alone, an under-sink system filters far more thoroughly for far less money. Whole house and under-sink solve different problems, and many homes end up with both.
Guides in this cluster
- Best whole house water filter systems — scored and ranked, with the right pick for city water and for wells
- How water filters work — the six mechanisms, and what a whole-house system can and cannot remove
- Do water filters remove fluoride? — why whole-house carbon is the wrong tool for this one
What a whole house filter does
It sits on the main line, before the water reaches anything else. That position is the whole point: it protects plumbing and appliances as well as the water you drink, which a point-of-use filter cannot do.
It also sets the limit. Because all the water in the house passes through it, a whole house system has to move a lot of water quickly, which rules out the slow, thorough methods used under a sink. Reverse osmosis at whole-house scale exists but is expensive and wasteful, which is why most whole house systems are sediment and carbon rather than RO.
City water or well water
This is the first question, and it changes the answer completely. City water arrives already disinfected, so the job is removing the disinfectant — chlorine or chloramine — plus sediment picked up in the pipes. Well water has no such treatment, so the job is iron, manganese, sulphur, hardness and sometimes bacteria. A filter built for one is close to useless for the other.