Why Your Washing Machine Has Low Water Pressure (explained)

There’s nothing quite so annoying as expecting something to be done only to find it hasn’t happened for some reason. One particularly annoying example of this is the washing machine. You load the machine, set the program, turn on the machine and walk away to get on with other household chores.

When you return 2 hours later, either the machine hasn’t finished, or worse still hasn’t even finished filling with water. So after doing some research, it turns out this could be caused by low water pressure, but what does that mean? And how do you solve it? Keep reading for the answers to both of those questions and more.

It’s Common On Modern Washing Machines

Back in the early days of washing machines, the simple mechanical design meant that the washing machine wouldn’t start their programs until the machine had filled with water. Which meant they were not dependent on a set amount of time to fill the machine to wash or rinse the laundry. The programs never started until the required amount of water was detected in the machine.

Modern machines nowadays are so much more sophisticated, and include so many safety features to protect our homes and families. Which is of course, great, however, it does mean that in some cases, if the machine detects low water pressure it will shut the program down.

The time it takes to fill the washing machine with sufficient water to run a program varies from manufacturer to manufacturer. Which means some are more time tolerant than others but if there is not enough water passing into the machine there’s the possibility of the program being aborted.

Washing Machine

How Low Water Pressure Affects Your Washing Machine

Modern washing machines are operated using a timer which starts as soon as the start button is pressed on the machine. The software is constantly checking that the machine has the correct water level for each preset time of the program. If that level of water is not as high as it should be at any given time during the cycle, the machine will issue an error code and abort the program.

This is a safety measure designed to ensure that your washing machine doesn’t flood your home or overheat and run the risk of burning your home down. Another factor is the design of the water fill valves, these need a certain amount of water pressure to ensure they shut off correctly. If the water pressure is too low it could allow water to keep running into the machine when the power is off leading to a potential flood.

What Causes Low Water Pressure?

There are a number of causes for low water pressure, however, here in the UK, water authorities guarantee a water pressure of 1 bar. Which is the amount of force needed to raise water to a height of 10 metres. This is easy to check, just turn on any tap in your home (but preferably the one furthest away from your stockcock).

Then time how long it takes to fill a 1 litre jug with water, if the time taken is 6 seconds or below, you have ample water pressure entering your home. If it takes longer than 6 seconds, contact your local water authority.

Why Does My Washing Machine Have Low Water Pressure?

Assuming that your water pressure is 1 bar and there is no issue of low water pressure in your area, you’ll need to investigate why your machine has low water pressure. There are a few reasons which could cause low water pressure in your washing machine which are;

  • Other taps being used at the same time within your home
    If you have other taps in your home turned on at the same time as the washing machine is running it could cause low water pressure. Check that all of your taps are off including any showers, outdoor taps, even a dishwasher. To be sure that this isn’t the cause, run a wash load when there’s nobody else at home and you’re sure you’ve turned off all other water taps.
  • Clogged water inlet valve filter
    This is another common cause of low water pressure to the washing machine. The water inlet valve filter prevents any dirt, grit or other debris from entering your washing machine along with the water. This can sometimes build up with debris and cause the water entering the machine to slow to the point of being too slow. To check this you’ll need to turn off the water supply to your washing machine. Follow the hose from the machine back to the tap. Then remove the inlet hose and inspect the filter. If it does look clogged gently brush away any blockage using a soft brush. Or gently remove the filter and replace it with a new one bought from your local DIY store.
  • Clogged inlet hose
    Sometimes the filter could be fine but the actual inlet hose itself could either be clogged or even bent. Straighten the hose or if it is already straight, remove it and try to remove any blockage. It might be easier to just replace the inlet hose as they are relatively inexpensive and can be bought at any DIY store.
  • Faulty pressure switch
    Every time the machine needs to be filled or emptied of water, it is the pressure switch which detects the water level within the machine. If the pressure switch is defective, it could send an incorrect message to the control board and the machine won’t fill with water. You can inspect the pressure switch yourself but unless you know what you’re doing, this is best left to a professional as it involves dismantling your washing machine.
  • Water supply tap not fully open
    It is also possible that the tap fitted to the washing machine inlet hose is not fully open. This could cause low water pressure and is simple to remedy. Just open the tap fully by turning it fully open.
  • Faulty tap
    Sometimes the taps themselves can develop a fault where even though they are allowing some water through, it isn’t at full pressure. To check this disconnect the inlet hose and time how long it takes to fill a 1 litre jug (it should take 6 seconds or less).

Are There Any Clues That Signify Low Water Pressure In Your Washing Machine?

If your washing machine has been running fine and suddenly develops a fault which you suspect could be due to low water pressure it is likely that you’ll hear a humming sound after the start of the program. Or it might make a banging noise accompanied by a lack of water. Or even the machine starts as normal but stops mid-cycle with no water in the drum.

What About Running A Washing Machine WIthout A Main Water Supply?

If you live in an area without mains water supply coverage, and rely on a bore hole, spring or well for your water, you will need to invest in a booster pump to ensure a sufficient water pressure to operate a washing machine. It would need to be a pressure activated pump and not a flow operated pump.

Some washing machine manufacturers can adjust the time limit on their machines to allow extra time for their machines to fill with water. You’d need to contact the manufacturer directly and ask if this is possible with your particular machine.

If your washing machine is supplied with water from a header tank as opposed to mains water, there needs to be at least 16.5 feet vertically from the bottom of the tank to the top of the washing machine. If this isn’t possible, you will need to fit a water pump, which again would need to be a pressure activated pump.

Frequently Asked Questions

What is the most common cause of low water pressure?

The most common cause of low water pressure is clogged or partially clogged pipes. Over time sediments can block pipes and cause the water pressure to lower.

Can I run my washer with low water pressure?

You can run your washer with low water pressure in some cases, you’d need to contact your washing machine manufacturer and ask them about your specific machine. In the UK water authorities should provide water at, at least 1 bar of pressure. Which is more than adequate to operate washing machines.

What controls the water flow in a washing machine?

The water inlet valve controls the water flow in a washing machine. If the water continues to flow after the machine has finished, this could be caused by the inlet valve sticking or insufficient water pressure to close it.

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