All you need to know about water accumulators in two minutes

Water accumulators, aka accumulator tanks might look like a simple water storage unit, but inside there’s magic going on!

What is a water accumulator?

Accumulators act like a giant pressure vessel with two chambers – one that’s pressurised with inert gas and sealed, the other that’s open to your water system. In between you’ve got a rubber membrane or diaphragm. You connect the whole thing up to be fed by the cold mains and can boost the pressure and flow to your hot water and cold water inside your home. For extra oomph, add a pump into the mix.

How does a water accumulator work?

If you’ve got low pressure going in to your cold water and hot water system, you’ll have low pressure water coming out! An accumulator tank work to fix that pesky problem. It simply stores cold water and helps water flow. It does this be naturally accumulating water at low demand periods (for example when you’re asleep or out and about) There are many different sizes of accumulator, so ask your plumber to recommend what size you need.

If you’ve got water running (eg you’ve turned a tap on), the accumulator boosts the flow of water to make it seem like it’s increased your pipe bore size and your water pressure. In reality, though, it’s just using the additional water you’ve stored and upped the flow! Adding in a pump is what gives the whole system pressure a leg up.

What fills up, must eventually empty and this is the case with accumulators. For example, if you run a bath over 100 litres and you’re accumulator has a 100 litre capacity, on the 101th litre the accumulator will have exhausted it’s reserve. Flow and pressure will revert to whatever your house is fed by. 

But straight after The accumulator will fill with water when there’s no demand, ready to boost for the next demand.

That’s why sizing an accumulator is so important!

What are the pros and cons of water accumulators?

We love a good water accumulator, but there’s definitely pros and cons to them.

On the plus side, they improve your flow rate no end and they don’t need electricity to fun, so they’re pretty eco-friendly. They also don’t take a lot of looking after apart from an occasional pressure re-charge.

On the minus side, they don’t come cheap (four figures and up!) once you’ve added in the pipework as well; and you may still need a pump on top of that. You also have to find somewhere to put a water accumulator, and they’re not exactly small! You’ll also need to comply with whatever regulations are in your local area. Be it on feed back into the main (stopped with a non return or ‘check valve’) or a Legionella risk management.