Low water pressure and washing machines

Low-water-pressure Low water pressure has become a big problem for a minority of washing machine owners because of the way modern washing machines work. Some people find that even though their old washer may have been slowed down by a lack of good water pressure it was still able to complete a wash cycle, yet when they buy a replacement it sometimes refuses to work.

Why is water pressure so critical now?

Stop-watch In the past, washing machines were controlled by simple mechanical program timers. When filling with water the timer motor in the programmer was turned off. The whole program came to a stop until the pressure system detected the right level of water had been reached. It then powered up the timer motor and the washing machine commenced washing or rinsing. This system was highly tolerant of low water pressure because it wasn’t dependent on time, it was just dependent on getting the correct amount of water inside eventually.

Washing machines are now far more sophisticated and most are controlled by software built into PCBs which runs like a computer program. This is an excellent advancement and brings lots of safety features and efficiency improvements but one side-effect is that without a high enough water pressure many washing machines will detect a fault and abort the program – even if the same water pressure has sufficed for many years with the old washing machine.

Time-out The amount of time allowed can vary from machine to machine so some washing machines are more tolerant than others (more on this later). Some washing machines may allow too little time to fill and abort the program unnecessarily at times. The fact that the previous washing machine worked perfectly OK with the old mechanical timers tends to back this thought up.

How does low water pressure affect a washing machine?

When reaching a fill section the programmer now no longer shuts off. Instead, the clock is ticking and the software constantly checks to see if the correct water level has been reached. There is a pre-programmed time limit, and if the correct water level has not been reached before this time then the program times out, triggers an error, and aborts the programme.

Why do they do this?

Setting a predetermined time limit for specific events is a good method of averting potential disasters and preventing things like flooding or overheating. There is a genuine safety issue if water pressure falls below a certain level because the washing machine fill valves need a minimum water pressure in order to close off properly. When setting the time limit though, some manufacturers may set it too cautiously.

What can you do if you have low water pressure?

There may not be an easy answer, especially if you don’t have access to a mains water supply and rely on a bore hole or well to supply water. In these cases you would need to research using an adequate booster pump, but it must be a pressure activated type i.e. pressurises the house water system to approximately 2 -5 Bar (depending on pump used) even when off. You cannot use the flow operated type (as used for shower pumps)

Here are some things you can try –

1 Make sure the tap supplying the washer is turned on fully, and that no fill hoses are kinked. Also make sure the tap isn’t faulty. The ubiquitous taps with the blue and red levers in particular can often partially seize up inside, become caked in sludge inside, or the plastic operating lever can crack meaning that the tap appears to be fully on but it isn’t.

2 If the low water pressure is only to the washing machine and you’ve done the first checks get the plumbing checked. If it’s just general low water pressure all over the house and you have already got the main stop cock on full get in touch with your water company who may be able to help. Water companies in the UK are obliged to supply mains water at a minimum pressure of 1 Bar, which should be high enough for a washing machine.

3 Don’t use those self-tapping self-plumbing taps that just clamp on to the copper pipe and pierce a hole to “tap” into the plumbing. Most of them pierce such a small hole (and often not cleanly either) that you probably won’t get a full water flow. In border line cases it may be enough to prevent the washing machine getting the right amount of water in time.

4 If washing machine is supplied with water by a header tank instead of mains then it needs to be high enough. However, raising it may not make enough difference unless you can raise it enough. Here’s what Electrolux’s technical spokesman told me -

“.. in order to obtain the minimum pressure, there should be a minimum vertical distance of 16.5 feet from the bottom of the tank to the top of washing machine, if this is not possible i.e. a bungalow or flat, then the only other option would be to fit a pump, but this must be a pressure activated type i.e. pressurises the house water system to approximately 2 -5 Bar (depending on pump used) even when off. You cannot use the flow operated type (as used for shower pumps)”

5 If your washing machine is a Miele, it may be possible for one of their engineers to adjust the time limit on your machine to allow a little longer to fill. I don’t know any other manufacturers that can do this, and especially doubt most ordinary ones do but you could always try asking. If nothing can be done and you can’t fix the problem you may need to replace the washer with one more tolerant to low water pressure (mentioned below).

My Research

Miele’s technical manager has told me that their machines will work down to almost half a bar so anyone affected must have a very low water supply. Also, Miele washing machines can be adjusted by a Miele engineer to adapt more to low water pressure situations. I’m not sure exactly what they do but I suspect they can increase the amount of time allowed for filling. It’s a sign of the extra sophistication you get with Miele product but of course this is likely to be a chargeable service as it’s not addressing a fault on the machine. However, it should rescue you if you just laid out for a new Miele, which didn’t work due to low water pressure and the water pressure was only just too low.

Please note / Summary

The vast majority of people have perfectly adequate water pressure. This article is for those who are aware that they have very low water pressure, or for those where their water supply may be from an unconventional source such as a bore hole or well. In such cases some sort of pump booster would be needed if pressure was too low to run a modern washing machine.

What is 1 bar of water pressure?

1 bar is a pressure that’s capable of supplying water 10 metres high. So if water was fed to a pipe at ground level that was 10 metres tall there should be enough water pressure for the water to come out at the top of it.

Water companies in the UK are obliged to supply mains water at a minimum pressure of 1 Bar. Washing machines should be designed to work on a minimum of 1 bar so unless you have an unconventional supply you shouldn’t (in theory) be affected. I’ve been told by an Electrolux that their washing machines will work with a minimum of .5 a bar. Miele washing machines need at least 1 bar.

If concerned about very low water pressure, ask your local water authority what the water pressure is to your home (Water companies’ contact details). If they say it is 1 bar or over then modern washing machines should work. If not you would need to complain to the water authority that your supply isn’t good enough to use a washing machine with.

Of course you need to make sure nothing within the house is restricting the water flow like the stop tap being turned down low.

UPDATE: I’ve managed to get a comment from a technical person at Electrolux who make Electrolux, AEG, Zanussi and Tricity washing machines which may be of use to anyone with known low water pressure such as water supplied from wells or tanks -

“All of our washing machines are now electronic and incorporate a maximum time fill of 10 minutes, the minimum water pressure required is 0.5 Bar (Maximum 8 Bar), this minimum pressure is required to ensure that the valve closes completely, (if less than 0.5 Bar there is a possibility of water entering the machine even when off electrically).

In low water pressure areas, we recommend that the machine is tank fed, but in order to obtain the minimum pressure, there should be a minimum vertical distance of 16.5 feet from the bottom of the tank to the top of washing machine, if this is not possible i.e. a bungalow or flat, then the only other option would be to fit a pump, but this must be a pressure activated type i.e. pressurises the house water system to approximately 2 -5 Bar (depending on pump used) even when off. You cannot use the flow operated type (as used for shower pumps)”

Anyone looking for a pump to increase their mains water pressure should try this Google search Search Google for pump increase water pressure

Further update: Oct 2010

A comment from Tim has highlighted a Panasonic washing machine, which he says works as low as 0.3 bars and has got it working in his low water pressure situation Comment 51

Update: May 2011

A comment from Faith highlights the problem of very low water pressure causing the washing machine water valve not to shut off properly allowing water to seep into it overnight. This shows the reason why manufacturers say you need a certain minimum water pressure although in this particular case it was caused by a faulty tap that didn’t actually shut all of the water off reducing the water pressure down so low the valve couldn’t shut of.

It does seem a very flawed method of stopping water from entering a washing machine, that is, using the pressure of the water itself to shut off the valve – when if the pressure falls below a certain level it fails to shut it off.

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Comments

  1. This has been a really useful article as we have just been told that
    problems with our new John Lewis washing machine are down to low water pressure. Our water is drawn by pump from a well. What is the best method of increasing the pressure?

  2. There are pumps designed to pump water from basements to supply a washing machine by companies like saniflow. They can bring water pressure up to the required level. You’d need to research if this is appropriate for your circumstances and how you would connect one.

  3. avatar Joe Frannino says:

    Your article expalined the mystery as to why my 4 month old GE washer keeps overflowing. Twice the water that oveflowed was minimal and easily cleaned up with a towel. The third time it flooded 3 rooms. GE tech came out and found nothing. I mentioned your article as to the problem coming from low water pressure suplied by the water well. He said it was not possible. Have you done any additional research on this problem and is there anything I can do other than stand next to the washer while washing? I was not at home the last time it overflowed but from the amount of water (oveerflowed over the outside porch) I doubt a pan under the machine would have been able to contain the water. Do they still make washing machines using the old method of checking the water level? May be cheaper to buy a new washing machine with the old technology than having to replace hardwood floors and sub floors.

  4. Hello Joe: As far as I know all washing machines in the UK now use software built into a control pcb to run programmes as opposed to the mechanical clockwork- timers of the past.

    The only way your low water pressure could be associated with a leak is if it is too low to shut off the water valve properly. This could allow water to slowly seep into the soap dispenser where water goes into the machine. It’s less likely to cause problems whilst the washer is running apart from the aborting problem due to timing out on fill.

    If a washer connected to very low water pressure isn’t shutting off the valve properly then a washer could start to fill up with water inside the drum overnight and eventually run out of the dispenser drawer or other places.

    Anyone concerned about this should turn off the taps each time they finish washing. However, I would speculate that if anyone’s water pressure was so low as to allow this, then the modern washing machine should probably not work properly as described in this blog article. This is precisely why manufacturers introduced time limits for fill. Turning off taps when the washing machine is not in use is definitely wise, and advised by all manufacturers.

    In other words, manufactures are deciding that if your washing machine doesn’t supply a certain amount of water in a set time they don’t think your water pressure is high enough and may have problems closing the valve off properly, so they refuse to work.

    If low water pressure is the cause of your flooding you should be able to see a slow dripping of water in the soap dispenser with the drawer taken out and you should be able to see that water is filling up inside the drum when not in use. ( NOTE: another cause for water running into the washing machine when not on use is siphoning from an incorrectly fitted drain hose connected to the u-bend – Washing machine fills with water overnight or when not in use )

    The problems raised with the blog article are that it’s often a bit of an arbitrary decision because the time allowed is clearly set too low with some washing machines. This accusation is valid because some people have used a washing machine without any problems for many years, but when they replace it with a software controlled one it keeps aborting on fill and will not work. However, a washing machine obviously will work OK because their old one did.

  5. To follow up my experience with the John Lewis washing machine – two engineers’ visits resulted in the conclusion that the water flow was too low. However each time the error message was something like ‘Check hose and connector’. I realized that neither engineer had really done anything about this this as they were so convinced it was low pressure. So as a last-ditch attempt to sort the problem, I removed the hose which incidentally has a fail-safe valve built-in, reversed it and flushed it through via the tap. Nothing came out but – -touch wood on reattaching the hose correctly the problem seems to have disappeared for the time being!

  6. avatar John Moore says:

    We have low water pressure. The system is gravity fed from a holding tank fed by water pumped up from a spring. By the time it gets to the kitchen taps water pressure in the hot and cold taps is about the same, the hot tank outlet being maybe 2.5m above the taps. There is a header tank about 1m above the hot water tank. The washing machine inlet is about another 1m lower than the kitchen taps. Is this sort of pressure likely to be sufficient to run a modern washing machine, as our old one an Indesit 1063W has about had it?

    Presumably I could measure the water pressure at the washing machine inlet by attaching a hose and seeing to what height the water rises? I seem to remember 1 bar being 10m head of water?

  7. Hello John:

    I’ve added an update to the bottom of the original article (scroll back up to it), which you may find helpful. I would go for an Electrolux washing machine to be on the safe side as they say they only need half a bar water pressure. That I presume means 5 feet of pressure instead of 10.

    If still having problems you would need to try doing something about it as mentioned in the quote from the Electrolux spokesman.

    Electrolux are one of the best makes in the mid price range, I reviewed one here – Electrolux EWN 14991 W Time Manager washing machine review

  8. avatar John Willis says:

    A really useful article, thank you, but can you suggest a way out in my situation? I have bought a new Miele machine – expensive but with a free 5 year guarantee! – and did not discover it requires 1 bar of water pressure until getting to the technical spec at the back of the manual (buried deep inside the packaging). I only have about 6m of fall from my cold water tank to the machine, which aborts every time I try to wash with it, with the Check Inlet light flashing all the time. To connect the mains to the machine will be an expensive process as it is an old rambling house where lots of bits and pieces have been added on by everyone who has lived there. And I could have bought a Zanussi and saved myself the trouble.
    Miele say they have no responsibility as there is no fault with the machine; they won’t take it back because I have started to use it; and the retailer disclaim any responsibility too. Surely suppliers should make this kind of thing clear before you buy?
    Have you any suggestions on getting round this, or comments on what my rights are?

  9. John:

    This is a very awkward problem because it’s hard to find someone to blame. In reality most homes have much more than 1 bar of water pressure. The problem seems to occur mostly when someone (like yourself) has connected their washing machine up to a non-conventional water supply such as a bore hole, well, or a gravity fed storage tank.

    Most washing machine manufacturers design their machines to work on at least 1 bar. As I mentioned in my main article Electrolux (who also make AEG and Zanussi) are particularly generous with the time allowed for fill, and their technical spokesman says they will work on just half a bar.

    Miele (amongst other manufactures) have made a decision to play it safer and insist on at least 1 bar. Their machines should work with any mains plumbing*, which is available in the overwhelming majority of cases. They say that less than that could adversely affect the water valve’s ability to shut off properly. However, I expect there is a margin built in. Let’s say a washing machine has just 1 bar of pressure but whilst the washer is filling there is a drop in pressure due to peak demand or someone drawing off water elsewhere. The pressure could drop below the required amount.

    You could argue that’s what the program software is supposed to protect against though, and it should be sufficient to produce an error in such an instance and abort the programme. The counter argument to this is that if starting off with only half a bar, if pressure dropped enough to stop the valve shutting off then aborting would be futile. This is because the valve would simply not be able to shut off unless enough water pressure returned. (Water valves in washing machines need the pressure of the water to shut off properly. It sounds bizarre but it’s always been so)

    Who’s to blame?

    The dilemma is in deciding who’s fault it is that your new washing machine won’t work and therefore who should bear the cost of it being replaced. It’s hard to blame Miele as they are designing to work on mains water pressure in a safe manner as they always have done. It’s hard to blame the retailer because they didn’t know you would be connecting it up to such low water pressure. Sales staff would be as unaware of this issue as the public and it may only be one in many thousands of customers that aren’t connecting the washer to the mains water supply. That only leaves you, and you aren’t to blame either. How could you possibly know the Miele wouldn’t work? Especially if your previous washing machine did work.

    If I was forced to blame someone, I wouldn’t be able to although it’s the seller you have the argument with in UK consumer law. You could always ask what Citizens advice think.

    The most desirable option would be if possible to keep the Miele and connect up a booster pump. This would solve the problem for all future washing machines too. I’ve made enquiries about if such a booster pump is available and will let you know if they are fruitful.

    *All water authorities are legally obliged to supply water at a minimum of 1 bar in the UK. Therefore any washing machine sold in the UK needs to work on a minimum of 1 bar. If a washing machine connected to the mains water supply does not work because of low water pressure and you know you have the stop tap adjusted correctly then the local water authority should be obliged to ensure you are supplied at a minimum of 1 bar of pressure.)

  10. avatar John Willis says:

    Thank you ever so much for this – I have only just realised you replied.

    I have talked to CAB & Trading Standards and all agree with you that no one can be blamed. I am still trying to come up with ideas as all the plumber can suggest costs many hundreds of pounds in his labour. He has meanwhile fitted a flexible hose from our outside mains tap. If you can find a suitable booster pump that would be great. He has measured the pressure as 0.95 of a bar but that still isn’t enough for the machine.

  11. John:

    The enquiries I made lead to a company who make booster pumps and they suggested “if noise is not a problem I would put these two products together..”

    Unfortunately the two products cost nearly £200, would probably need fitting by a plumber and looked bulky and by their own admission noisy. I decided it wasn’t an ideal solution at all.

    If you are getting 0.95 of a bar I will contact Miele and ask their technical guy if it’s possible to adjust the time somehow to make it work. It’s a long shot but I will let you know what he says.

  12. avatar John Willis says:

    Brilliant, thanks

  13. John:

    I’ve refreshed the main article adding more information although nothing approaching a cure-all I’m afraid. I’ve been in touch with the Miele technical guy and still trying to clarify whether they are able to adjust anything I’m afraid. I will post further info asap.

    Miele told me that their machines should work with as little as about 0.6 bar.

  14. avatar John Willis says:

    Thanks to your latest advice and the plumber’s measurements of pressure in my system, I have now made more phone calls and made some progress. Whereas first time, Miele Customer Service told me there was nothing I could do, I have now been told they will come out and adjust the settings to take a lower pressure – for free!

    I cannot believe we have had so much hassle when they could have suggested this earlier. Thanks again for your help.

  15. Thanks for the update John. I spoke to the guy in charge of the technical side at Miele and he said they would have a look for you but I didn’t receive a reply when I followed it up by email.

    Please keep us informed. I hope it can be resolved asap.

  16. avatar John Willis says:

    Yes Andy, it’s sorted. A Miele engineer finally came and in 1 minute adjusted the time it takes to fill, and it works fine. He couldn’t understand why there was nothing in the manual about it, because he says it is possible to do it yourself manually! I think he is absolutely right, and it should be included in the spec for the machine etc as well, and retailers should know how to deal with the problem. I was thinking of writing a complaint to Miele, but some one suggested it might be better to ask Which? to do it – as you know the problem must be quite common. Anyway, thanks for all your help on this.

  17. Great news John. It’s unfortunate that it took so long. I don’t know how you managed.

    If the adjustment could be made available it would be much better. However, unless the code or special button combination to get into the configuration only affects the time taken to fill they wouldn’t want people to have access to it.

  18. avatar Steve Leung says:

    I have a Bosch Exxcel WAE24467GB washer. I live in a top floor flat with storage tank fed cold water supply. The machine works ok but has posted a few low pressure error codes (4-5 times) but on the whole works ok. I’m guessing my water pressure is borderline. Will I make things drastically worse, do you think, if I use the cold water supply to feed a coffee machine that needs plumbed in. I propose to split the supply with a T-joint and use 3/8″ tubing to connect the two appliances. The length of connections is very short. I just bought a water pressure gauge but I see that you have to measure flow to accurate predict whether the flow will be enough for the machine. I don’t want to purchase an expensive coffee machine, plumb it in, and find that the washing machine is affected! Any advice would be much appreciated!

    Steve

  19. Hello Steve: I can’t claim to be an expert on plumbing but this is how I see it –

    I don’t think splitting the supply would affect the water pressure to the washing machine as the supply to the washer would presumably be the same as it is now. If you just split the supply to run off a short distance to another appliance then only when that appliance is taking water should the pressure to the washing machine be affected.

    When the other appliance isn’t drawing water, then the water would just run up to the appliance and reach a dead end. I would expect as it’s not drawing any water it couldn’t be diverting any water pressure from the washing machine.

    That’s how my logic sees it. I hope it’s right.

  20. Very interesting! I’m about to order a Bosch WAE24467 washer
    but I’m worried about our low water pressure which is caused by furring up of the metal supply pipe running from the road under
    the garden and the house to the rear of the property. It can only
    worsen over time but is apparently my responsibility. Our existing
    Bosch washer has refused to take powder and conditioner from
    the tray for quite a while now but using wash tablets in a bag in the drum has overcome that problem. Items needing fabric conditioner have to be rinsed in the sink and spun again—very
    time-consuming.So the question is; can the water co. be pressured
    (forgive the pun) into putting this right?

  21. Barry: I understand they are obliged to supply a minimum of 1 bar pressure to your house. It depends where their delivery point officially starts though logically it should be at your main kitchen tap.

    However, there is a difference between water pressure and water flow so they may well be supplying sufficient pressure but if the water flow is reduced by furring of pipes that’s possibly another matter.

  22. Thanks Andy. I’m pretty sure the water co’s responsibility ends at
    the property boundary; hence the scary junk mail from utility co’s
    offering insurance against leaks in supply pipes underground
    though a trawl of the small print reveals my furry pipes aren’t
    covered.

    I’m going to try an old Indesit machine I have which is ok down to
    0.5 bar, according to the instruction booklet. I’ll let you know in a
    week or so.

  23. Please do Barry: I wonder why the pipes are only furring up from your boundary onwards? Have they said what they blame for the furring?

    Unless the bore of the pipes to your boundary is much bigger than the ones taking the water into your house it doesn’t make sense why only your pipes are furring.

  24. The supply pipes from the mains in the road are metal and only
    about 1″ diam. The furring is part corrosion, part deposits. Sounds
    like a recipe for disaster if the corrosion causes a leak.

    The new spare machine works fine but, like the old one, doesn’t take up the fabric conditioner. I think my only remedy is to ask
    the water co. to install a new supply to the back of the house
    where my existing stop-cock is.(The back wall is on the boundary
    of the property) This would entail the new supply going about 15mtrs under a footpath.

  25. avatar lindsey says:

    Hi i bought a bosch28363, a couple of days ago, ahd it all connected up, but wont work it keeps giving me the error code for low water pressure. My old hoover machine worked marvellously for a few years. I am connected to the mains supply. What can i do..

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