What types of home water filter are there?
Ayus installs and maintains 4-stage water filters at home, hidden under the kitchen sink. Our filter uses ultrafiltration, but we know that anyone looking for a filter comes across three main options: reverse osmosis, ultrafiltration and the filter jug.
There is no single right choice for everyone. Each one works differently and leaves different water in your glass. It is worth understanding how.
How does reverse osmosis work?
In reverse osmosis, water is pushed against a membrane so fine that only water molecules pass through easily. Almost everything else stays behind: salts, minerals and particles.
To stop the membrane clogging, the system keeps rinsing away what it holds back with part of the water, which goes down the drain. The proportion depends on the equipment. Many systems need an electric pump to get enough pressure, and a tank, because the water comes out slowly. As almost all the minerals are removed, some systems add a stage to put minerals back in.
How does ultrafiltration work?
In ultrafiltration, water passes through the walls of hollow fibres full of very small pores. In the Ayus filter, these pores measure [X] µm. Anything larger, such as microplastics, bacteria and fine particles, stays on the outside.
Minerals such as calcium and magnesium are dissolved in the water and pass through. So the water keeps its character. Ultrafiltration works on mains pressure alone: it needs no electricity or tank, and it throws no water away. We explain the 4 stages in how it works.
What about a filter jug?
A filter jug mainly uses activated carbon, sometimes with a resin. It is cheap and easy to start using. It reduces the chlorine taste and, depending on the cartridge, some other substances.
It has limits: it filters little water at a time, takes up space in the fridge and the cartridge has to be changed often. What it holds back in terms of particles depends a lot on each model’s filter.
Side-by-side comparison
A summary of what each option does, point by point:
- Chlorine taste: ultrafiltration with activated carbon removes it; reverse osmosis removes it; the jug reduces it.
- Microplastics: ultrafiltration holds them back (pores of [X] µm); reverse osmosis holds them back; with the jug it depends on the filter.
- Minerals: ultrafiltration keeps them, and the Ayus filter adds magnesium; reverse osmosis removes almost all of them; the jug keeps them, in part.
- Water thrown away: with ultrafiltration, none; with reverse osmosis, part of the water goes down the drain; with the jug, none.
- Electricity: ultrafiltration does not need it; reverse osmosis often needs it, for the pump; the jug does not need it.
- Where it goes: ultrafiltration and reverse osmosis go under the sink; the jug goes in the fridge.
Which one should you choose?
If you want the purest water possible and do not mind losing the minerals and part of the water, reverse osmosis does that. If you only want to mask the chlorine and drink little water, a jug may be enough.
If you want water that tastes good, with no chlorine, no microplastics and with its minerals, always ready at the tap and with no waste, ultrafiltration is the middle ground. Not sure about your kitchen? See the FAQ.
