The complete guide
Sizing a water filter for the number of people using it
Capacity is the specification people get wrong most often, in both directions. Buy too small and the filter is permanently empty. Buy too large and you have donated a third of your worktop to an appliance that is mostly full of water you are not drinking.
Start from litres per person per day
The usable planning figure for a UK household is 1.5 to 2 litres of filtered water per person per day — and that is total draw, not just glasses of water. It includes the kettle, the coffee machine, cooking, and topping up bottles before people leave the house.
That gives you a rough daily requirement:
| Household | Daily filtered water | Sensible tank |
|---|---|---|
| 1 person | 1.5–2 L | 2–2.5 L jug |
| 2 people | 3–4 L | 3.5 L jug |
| 3–4 people | 5–8 L | 6 L or a dispenser |
| 5+ or an office | 8 L and up | 8 L+ dispenser |
The tank should cover about a day. Not a week — water that has stood for days in a warm kitchen is not what you want, filtered or otherwise.
Refill frequency is the thing you actually feel
A useful way to think about it: how many times a day is someone going to have to walk the container to the tap?
With a 2-litre jug and four people, that is three or four refills a day, every day. Each one is trivial. Cumulatively it is the reason the jug ends up sitting empty in the fridge while everyone drinks from the tap instead, which defeats the entire purchase.
At 6 litres and the same four people, it is roughly one fill a day. That is a habit people actually keep.
Why bigger changes the format
Past about 4 litres, the sensible design stops being a jug and starts being a dispenser, for two reasons:
- Weight. Six litres of water weighs 6 kg. Add the vessel and you are lifting 8.6 kg with one hand at an awkward angle. Nobody pours a 6-litre jug twice.
- Filling in place. Large containers are designed to be filled where they stand and dispensed from, either by tap or, as here, by button.
This is why the ED04B has a dispensing spout rather than a pouring lip. You are never meant to pick it up full.
Do not size up to solve the wrong problem
A bigger tank fixes "we keep running out". It does not fix:
- Limescale, which needs hardness reduction — see the ED06W.
- Wanting hot water on tap, which needs a heated machine like the BRITA YOURCE mini.
- Dissolved solids, which needs reverse osmosis.
If the complaint in your house is volume, size up. If it is anything else, the extra litres will not help.