Is a water purifier worth it?

The advantages, in order of weight

Not in order of how well they sound, but of how much they actually change the day.

You stop carrying the crates

This is why most people switch, and it is almost never top of the list on sites that sell. A household of three drinking a litre and a half each a day moves around 1,600 litres a year: that is roughly 110 six-bottle crates to carry up, store somewhere and then throw away.

The water always tastes the same

A reverse-osmosis system removes much of what gives mains water its taste, starting with the chlorine used to keep it safe, and then remineralises it. The result is steady: it does not change with whichever brand is on offer.

You make the sparkling water at home

If sparkling water is drunk in the house, the carbonator removes the other half of the crates. It is also the item that makes the sum easiest, because sparkling bottled water costs the same as still and weighs the same.

Less plastic

Around 700 fewer 1.5-litre bottles a year for that same household. It is a real benefit but an indirect one: people who switch for this reason usually had another reason already.

The limits, which are real

None of these is a hidden defect: they are how a reverse-osmosis system normally works, and it is worth knowing them beforehand.

• It sends some water down the drain. The membrane separates the filtered water from the stream carrying the salts away: a share goes to waste. On the bill it is worth little, but it is there.
• Reverse-osmosis water is low in minerals, which is why domestic systems remineralise it after filtration. If a system does not, the water comes out very light: that is a technical choice, not a detail.
• The filters have to be changed, and if you do not change them the system gets worse rather than better. Anyone who buys has to remember; anyone on a service sees them arrive.
• It takes up space and wants a socket. Under the sink you need roughly 50 × 55 cm clear and a power point nearby.
• It is not instant. A domestic system produces a few litres an hour: you fill the jug, not the bath.

When it is not worth it

The four cases where the answer is no, and they are real cases.

If you drink little water

Below a litre a day per person, any monthly formula costs more than you would spend on bottles. The sum is done on your litres, not on an average.

If you already buy the cheapest water

At twelve cents a litre, a household of three spends around €190 a year. No monthly fee comes in under that: what you gain is not carrying the crates, not money.

If the problem is limescale

Limescale in the radiators, in the washing machine and on the taps is a water softener's job, and a softener treats all the water in the house. A purifier works only on the water you drink. They are two different things and sometimes you need both.

If you are about to move

A system you have bought has to be taken out and refitted; a contract with a minimum term is paid anyway. Better to wait until you are where you are staying.

How to decide in five minutes

Three numbers and one question:

• How many litres you drink at home in a week. Count the bottles, do not go from memory.
• What you pay per litre for the water you usually buy. Take the receipt.
• What it costs you a year: litres × price. Below €250 the sum in money almost never adds up.
• How much of a chore carrying them is. If the answer is «quite a lot», the sum in money is not the only one that counts.

If you would rather test it than work it out on paper, the 30-day trial is exactly for that: the system in your kitchen, nothing paid up front, and the decision afterwards.