Water pressure explained

It isn’t unusual for a homeowner to experience low water pressure problems at some point, whether it be a slow running tap or a washing machine that takes forever to finish its cycle. It is a common complaint that the Maintracts team encounter on a weekly basis. In this blog, we explore water pressure and water flow, what pressure you should expect, various issues that you may encounter and hot to measure the water supply.

What is water pressure?

Water pressure is the measure of force used to move water through the mains and into the pipes in our homes, businesses, and community areas.

What is the normal water pressure for a house?

In the UK, water pressure (how forceful your water is) is measured in metres per head or ‘bar’.  Water suppliers have an obligation to provide a minimum of 10 metres/head (or one bar) of mains water pressure.  This means there is enough force/pressure to push the water to a height of 10m.

This is measured at the point where the water leaves the water suppliers pipework at street level and enters yours.

Water pressure can vary greatly depending on where you live, which room in the house you are in and even what time of day it is.  We tend to find that older, high-rise properties in London or properties in more elevated areas, experience problems with low water pressure as the pressure reduces by 0.1 bar per metre as water travels upwards (against gravity).  Similarly, water flow can also be reduced for the same reason, with some properties experiencing water starvation. This can be a particular problem where older houses are converted into multiple dwellings which all share a single mains water supply.

No matter how good your water pressure is initially, demand for water will also affect it.   Water pressure can decrease during periods of peak usage, particularly in the mornings when the majority of households are using their bathrooms and kitchens simultaneously.  Summer evenings often cause a dip in pressure as people water their gardens.

What is the difference between water pressure and water flow?

Here at Maintracts, we find there is a common misconception among homeowners that water pressure and flow are the same thing or are directly related to one another, but they are in fact two different things:

As we have already discussed, water pressure is a measure of forceWater flow is a measure of volume i.e. how much water is flowing through your pipes or an outlet (such as a tap or shower) at any one time.  Water flow is measured in litres per minute.

It’s important to understand that whilst water pressure and water flow are two different things, the water flow rate from an outlet is often a good indicator of your overall water pressure.  However, this may not always be the case and shouldn’t be assumed, for example, the water pressure being supplied to a property might be good and at the right measure, but if the pipework is undersized or there is a faulty valve or some kind of obstruction – the water flow can be reduced.

Why should I check the water pressure at home?

Checking your water pressure can not only save you money, it can also save you time and help ease the running of your household. If your water pressure is too high, you may be using too much water every day; if it is too low, you may find that simple tasks, like running a bath, takes forever, or your dishwasher and washing machines are taking longer to complete their cycles.

Checking your water pressure can also keep you abreast of any serious plumbing problems before they escalate.  Sudden changes in water pressure are not a good sign.  Decreases in water pressure and flow could indicate a leak or a blockage somewhere in your piping.  Alternatively, a sudden increase in water pressure could put undue stress on your pipes, fixtures, and appliances, resulting in wear and tear, drips, and leaks.  If you notice a change your water supply, you will need to determine the reason behind low water pressure in order to get the problem resolved.

How to measure water flow rate from a tap or other outlet

There is an easy way to measure your water flow rate which can give you an indication of your water pressure – don’t worry, it’s pretty straightforward!  All you need is a measuring jug, a stopwatch, and to follow the following five steps:

  1. Place an empty measuring jug (1 or 2 litres in size) under the outlet (tap or shower) you want to measure.
  1. Turn the outlet on.
  1. Time 6 seconds on your stopwatch and turn your tap or shower off.
  1. Multiply the amount of water in the jug in litres (say for this example it was 0.6 litres) by 10. This will give you your flow rate in litres per minute (in this example it would be 0.6 litres x 10 = 6 litres per minute).
  1. If your flow rate calculates as less than 10 litres per minute, you may have what is termed low water volume. Anywhere between 10 and 15 litres is acceptable but can be improved. A flow rate above 15 litres per minute is considered good.

It is commonplace for us to help customers with issues relating to the water flow rate being too low or even too high in their house, often as a result of taps and valves not being properly commissioned upon installation.  The majority of taps and showers on the market today are intended for connection to mains pressure or high-pressure water supplies, so they do not operate effectively when connected to gravity or low-pressure water supplies. We also find that some outlets produce too much water, so when in use the flow rate from other outlets in the property is greatly reduced. This can be especially noticeable in properties where the water supply is limited anyway.

If you have questions surrounding water pressure, the Maintracts team can help.  As trained professionals we can correctly regulate a system so that each outlet produces the appropriate supply of water, improving the performance of the overall system and also saving water.  Just give us a call on 020 8131 1866, and we’ll do the rest.