What is the best flow rate for a kitchen or bathroom?

OK! It’s time to buy a new tap for your kitchen or bathroom but how can you make sure the flow rate advertised is a good fit for your home?

Actually, it’s pretty easy and you just need to have a couple of bits of information to ensure that the elegant, shiny new tap you have your eye on is going to operate efficiently as well.

You will need to know what the water pressure is and that depends on where your home is in relation to the nearest reservoir/supply. For example, if you live in a valley, then it’s a pretty sure bet that the pressure will be high. But if you’re on top of a hill, the pressure naturally will be weaker.

Water pressure is measured in “bars”— 1 bar is equal to the force needed to push water up to the height of 10 metres. In general, you will find the pressure in your home is one of three types:

Low Pressure (Gravity)

Cold water tank in the loft and a hot water cylinder upstairs. Advice: Choose taps designed for a low pressure system.

High pressure (Combi-boiler system)

Boiler unit in kitchen with no hot water cylinder. Advice: free to choose from a wide selection taps.

High pressure (Pumped system)

Hot water cylinder with an expansion vessel, normally placed in an airing cupboard. No cold water tank. Advice: free to choose from a wide range of tap designs.

How to measure water pressure

If possible, it’s worth asking a plumber to check your water pressure but it’s not that difficult if you want to do it yourself. All you need is a stopwatch (your mobile should have one installed) and a 1 litre jug.

• Put the jug under the tap and turn it on.
• After 6 seconds turn it off.
• Then you multiply the amount of water in the jug in litres by 10.

So, say you have collected 0.5 litres – that x 10 would equal 5 litres per minute. We know that 10 litres a minute is 1 bar so that mean you have a low pressure system at 0.5 bar.

If you find a measure that is between 10 and 15 litres per minute, that’s not bad but can be improved, while a flow above 15 litres per minute is good.

Armed with this information on your water pressure, you can check the specifications of the tap you intend to buy and make sure it is a good match. If you have a low pressure system and you choose a tap with a very low flow rating that is not designed to work well with less pressure, then you will probably be more than a little disappointed.

With that low pressure and type of tap, it’s going to be tough to ensure there is a suitable mixed flow of water, simply because as the cold water from the mains is delivered at a higher pressure and will be stronger than your hot-water pressure.

Low pressure kitchen taps

For those on extremely low pressure we recommend that you select a mixer tap to suit a minimum pressure of less than 0.5 Bar. With quality brand you will still get a flow rate of 15 litres per minute. Grohe have developed a super range of beautifully designed low pressure kitchen taps. See them here.

High pressure kitchen taps

With high pressure systems, you should have little problem in choosing an excellent design with the right flow rate. See the range here.

Low pressure bathroom taps

You can find a good selection of quality taps with good flow rates that will handle a minimum pressure requirement of under 1 Bar. If you have extremely low pressure, it’s best to choose a mixer tap with a minimum pressure of less than 0.5 Bar. Well-designed models for low-pressure settings can deliver flow rates between 4-7 litres per minute. Take a look at what’s available here.

High pressure bathroom taps

If you have the benefit of a high-pressure system, then there is a great range of bathroom taps for you to choose from, with the right flow rate of around 5 litres per minute. See what’s available here.