Low water pressure has become a big problem for a minority of washing machine owners due to the way modern washing machines work. Some people find that even though their old washing machine 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 new one it sometimes refuses to work.
Why is water pressure so critical now?
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. 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. The wash cycle is controlled like a computer program. This is an excellent advancement and brings lots of safety features and efficiency improvements.
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.
The amount of time allowed to fill 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 can abort the program unnecessarily at times.
The fact that the previous washing machine worked perfectly OK with the old mechanical timers backs this 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.
The software constantly checks to see if the correct water level has been reached. If the correct water level has not been reached before a pre determined time limit then the program times out. This usually triggers an error code, and aborts the wash cycle. When setting the time limit though, some manufacturers may set it slightly too cautiously.
Why do they do this?
Setting a predetermined time limit for specific events is a good method of averting potential disasters. It can prevent things like flooding or overheating. Suppose there’s a big hole in something and the washing machine is trying to fill the drum – but the water is just pouring onto the floor.
If unattended this could be a disaster. So if the washing machine times out after 3 or 4 minutes because the water level hasn’t risen inside the drum, this is very desirable.
Also, if water pressure falls below a certain level there is another safety issue because the washing machine fill valves need a minimum water pressure in order to close off properly. This can cause water to seep slowly into the drum and is arguably a very silly design.
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 a well to supply water. In these cases you would need to do some research into using an appropriate booster pump.
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).
Miele washing machines
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 I 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.
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. 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.
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. 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.
5 things to try if you have low water pressure
Make sure the tap supplying the washer is turned on fully. Also make sure that no fill hoses are kinked. Ensure the tap isn’t faulty. The ubiquitous taps with the blue and red levers in particular can often partially seize up inside. They can 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.
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. This should be high enough for a washing machine. If you don’t think your water pressure is particularly low, test by disconnecting the fill hose(s) and running the water into a bucket to check the flow rate in case the low pressure is just at the washing machine’s tap.
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. If you have those taps fitted and especially if you didn’t have trouble in the past then getting them replaced with proper taps may make a big difference.
If the washing machine is supplied with water by a header tank instead of mains water then it needs to be high enough to create an adequate water flow. However, raising it may not make enough difference unless you can raise it high enough and that’s not always possible. 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. However, 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 can’ use the flow operated type (as used for shower pumps)
It’s possible that your water pressure may vary, and be slightly stronger or weaker at certain times of day, especially if you live in flats. At weekends or after work for example it could be that more people are drawing on the water. So try changing when you put the washing machine on. It’s a long shot, but if borderline it could make a difference.
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. Here’s what they said ..
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 Search Google for – pump increase water pressure
Further update:
A comment from Tim (below), 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.
A design anomaly or flaw with washing machine water valves is that very low water pressure can cause the washing machine water valve to not 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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Thanks for this it was very helpful, so thought I would feedback my experience.
I have a bore hole, and header tanks in loft of a bungalow. I measured the drop at around 12 feet, although you should be able to take into account the tanks being full or half full really, giving further drop.
I didn’t want a pump. So searched and emailed all over. Miele were very helpful but said I was borderline. Most other manufacturers were borderline, such as the AEG I considered, 0.5 bar is not the 0.4ish I have.
A new player to the market is the answer! The Panasonic NA-147VB2WG requires 0.3 to 1.0 bar!
Received it yesterday and first wash went fine. Looks very good build quality compared to my Indesit rubbish before. And Panasonic being a premium brand, I suspect to enter the market they will be selling at a very competitive price to get penetration…. well maybe
So another suggestion for all out there
Thanks
Tim
Oh and one other comment.
I spoke at length to Miele who had discussed with German technical department. They said there was no adjustment to there machines, as quoted in forum above. They work to around the 0.4 bar mark “out of the box”, and the issue is whether there is enough pressure to shut the inlet valve. That was what I was told.
Thanks for your contribution Tim: I will point to your experience and the Pansonic washing machine from my main article. I think the Panasonic is similar quality to LG and AEG though should as you say be better than an Indesit.
Regarding the Miele adjustment. It’s most probably true that they can’t adjust one to work OK with less than half a bar, but they can adjust them to take longer to fill without timing out so on borderline cases (over .5 a bar) it could help stop one aborting on fill.
No problem, this article helped me a lot, appreciated.
The Panasonic machines seem to be an unknown entity but there branding is hopefully enough . . . time will tell.
Thanks Tim: Funnily enough I wrote an article about Panasonic washing machines last week Pansonic washing machines It’s not so much an authoritative piece, just my thoughts.
Hi: I read your report on Panasonic machines, helped me to decide to buy one, thanks.
Also forgot to mention, the Panasonic machines are rated down to 0.3 bar in their manuals, which can be downloaded on line, so the risk is minimal. Max 1.0 bar which means they need pressure restrictors in a lot of circumstances, nice to have it my way for a change. I got a 4 year warranty when purchased through John Lewis via redemption.
Hello! I am so happy to have found this blog – I was starting to think I was ‘doomed’ and had some kind of washing machine ‘curse’. No kidding.
Thanks to Tim (#35. February 14th, 2009, at 4:40 PM.) I have finally been able to confirm that I definitively have low water pressure – just under 5 litres in one minute. However, I am still not sure if that is what is causing my problems, and I hope you, or someone, can help me – I do not live in Europe, and where I am there is no service, nothing professional to say the least. I can only call the store that sold me the machine, but they are not authorised to do repairs. They will only send some poor, abused, underpaid, mistreated and unskilled labourer to fiddle with the machine, and probably make things worse than they are now.
Namely, here’s the overview of the issues I have been experiencing. First I had an LG front-loading 7kg washer. All was well for about a year – except for the fact that loads would take slightly longer to complete than company predicted time, due to the low water pressure, which we suspected all along. Fine. Then the machine started ‘acting up’ – instead of a little longer, it would take 5-6 hours to complete a load! At the same time, water started leaking into the drum overnight – even with the tap tightly shut – and at one point flooded the kitchen. After that everything just started ‘dying’ – the heater stopped working (a 90 degree wash would not even become warm), the loads would just stall for hours in the same spot, then eventually finish up, etc.
Deciding the problems were too numerous to even attempt a repair, plus not really having anyone to contact for repair, my husband and I decided to invest into a new machine, one not so computerized – and that is when we went back to Whirlpool, the same model we were using for years at our previous place of residence without a single problem.
Except that now, with just a little over a year of use (and so outside of the warranty given by the store) the same ‘water filling the machine overnight’ issue is back to haunt us! Since we bought it we have occasionally had the issue of ‘check water inlet’ warning – due to low pressure – but this issue was simply resolved by pressing ‘continue’ button. Again, maybe the load would take a bit longer to complete, but this is understandable and we were ok with it.
We are not ok with the water filling the machine! Why is this happening – even with the tap in the wall turned off? We have removed the hose and we notice a little bit of a drip, a drop here and there, seeping through, but surely this cannot fill the machine overnight? And why now and not before?
Is this a plumbing issue? I hope it is because that at least we can attempt to fix with the landlord. Or is this a water inlet valve issue? Could the dripping have affected the valve inside the machine? How can we fix this ourselves, or can we at all?
I am sure it is not the drain pump – it is not connected to the sink, but has it’s own drain, an it is higher than the drum, like your diagram shows. Also, the water filling the machine is clean. We have checked the pump filter (I’ve been fairly regular in this since we bought it), there is nothing blocking it, the pump spins easily.
Please, please help. I realize that this is not a ‘repair’ discussion, and that you are probably overwhelmed with requests, but I just don’t know who else to turn to. If we cannot resolve this issue, I feel it will turn into the LG, and things will just ‘die’. We cannot afford to buy a new washing machine every year, and I cannot begin to describe the frustration and desperation we are feeling due to our lack of knowledge and utter helplessness.
Thank you.
Like many others, I am delighted to have found this article. I was particularly interested in Tim Reynolds’ contribution on 5th October 2010, which may well influence my purchase, but I think there may be an error. The Panasonic manual states 0.03 MPa – 1 MPa. The units are megapascals and 1 bar equals 0.1 MPa. Therefore the acceptable pressure range is 0.3 bar – 10 bar, not 1 bar as stated. I hope I’ve got this right, as I am no scientist (thanks wikipedia!).
I can still confirm the Panasonic goes down to 0.3 bar for me and we are very happy with its performance and noise :o))))
Hello Faith: Low water pressure could explain your faults but not really why they would only appear after a year both times.
Low water pressure can also be too low to shut the valve off and allow water to drip through into the machine. It can’t possibly come into the machine if the tap is turned off though, so if it isn’t coming in from the drain hose as described in my Washing machine fills with water overnight or when switched off article – and you say it isn’t even connected to the u-bend so it can’t be – then the only logical explanation is that the tap isn’t actually turning off the water when you think it is.
If you have one of the ubiquitous taps with a blue plastic lever to turn off the tap they are notorious for not turning off the time sometimes even when you think you have. This can easily be tested by disconnecting the hose from the washing machine with the tap turned off and seeing if any water still comes though.