There's an issue with our en suite shower that is currently puzzling us, and our plumber.

Our en suite shower is making a high pitched 'squealing' sound after about a minute of operation, this is accompanied by an apparent loss of pressure, as the water comes out at a slower rate.

To make it slightly more complicated, it seems to only be at certain temperatures. I have a warm shower, rather than hot, and that's when it occurs. My wife has a hot shower (ridiculously hot in fact, steam everywhere) and it doesn't affect her.

However to make things really confusing, if I have a shower on warm before my wife, and then she has hers, the issue will likely occur for her too.

And finally, we've found if we run the tap in our en suite sink at a decent rate whilst the shower is on, it fixes the problem.

We have 2 showers in our house, and altogether 4 sinks, along with a washing machine that is piped in, and none of them have any issues with water flow.

Our plumber replaced the shower [head], but that didn't help, and actually seemed to make it worse, with it occurring pretty much immediately. The shower [head] he replaced ours with has since worked fine in another house.

He did say our water pressure is extremely high, and indeed when we turn a tap on the water shoots out, so he wasn't sure if that had anything to do with it. He's stumped and he's now asking around to see if anyone he knows might have any ideas.

I was wondering if anyone else has had a similar problem, and has any ideas how to solve it?

Our house is only about 10 years old (we've been in it about 3 years), and we've only had this problem for the last 6 months or so without anything obvious changing.

I should probably mention that I'm not great with DIY, so explaining in layman's terms might be best.

  • Does your shower have a tub spigot - perhaps with a diverter (the lever that send water to the shower rather than the tub)? Often times the diverters vibrate (making a squeal) when the pressure is "just right". If you have one, wiggle it to see if the pitch changes.
    – mike65535
    Jul 26, 2019 at 17:52
  • When you say "en suite" are you intending to say that it's plumbing is connected to other plumbing fixtures? or just a normal bathroom that is part of your master bedroom? - en suite: adverb & adjective - In or as part of a series or set. -- In a set or connected series; forming a series or set with something else in the same style: as, apartments to be let en suite or singly. - adj. - As part of a set or series.
    – Alaska Man
    Jul 26, 2019 at 22:45
  • Is the valve one that has an anti-scald adjustment?
    – Alaska Man
    Jul 26, 2019 at 22:48
  • Sorry for the late reply, only just got an email just now to tell me this has had so many comments and answers, I mean en suite as in a bathroom next to the master bedroom, and it doesn't have a spigot for a bath, it's just a shower. I don't think the valve has any anti scald adjustment, just one for the temperature and one for the flow.
    – James R
    Jul 27, 2019 at 20:29

5 Answers 5


I know this is going to sound crazy but I had a similar problem with a cold water shower valve. It would squeal and then the pressure would drop. I ended up removing the valve stem and found a very loose washer. I replaced it and never had the problem again.....

  • +1 I agree that the first step should be disassembling the valve(s) and having a look-see. Jul 27, 2019 at 3:52
  • Thanks, I will have a look at the washers in the valve when I get chance. Like I said the plumber did change the shower, so really should get a new plumber if it is this.
    – James R
    Jul 27, 2019 at 20:35

It could also be the mixing valve. The way that showers adjust the temperature is via different openings of 'ports' in the mixing valve, and they can get clogged with stuff in the lines; turning them differently or different amounts of pressure could also affect the mixing valve.

Try unscrewing the cover and removing the cartridge -- I've had this problem with a sink faucet in the past.

  • 1
    Thanks, I will check the mixing valve too when I get chance to take the shower apart.
    – James R
    Jul 27, 2019 at 20:36

Get a new Plumber and I agree with gbronner. The mixing valve or anti-scald protection of the valve is the extremely usual cause of what you describe very well.

With the age of your home and therefore the shower valves, both baths' shower valve cartridges should be replaced. We're dealing with plastic and 10-years is the normal expected failure frequency of the "wonderful" garbage.

Yes, I said both showers. It doesn't matter how frequent or infrequent the valves are used, they're both always under pressure. Either one's failure allows hot and cold water to contaminate the other or take over entirely. A loss in pressure means one is taking over and traveling into the other that it stole the pressure from before making it out into the shower.

  • Thanks, will try gbonner's solution, and keep it in mind if the other shower displays the same behaviour. We do use that a lot less though.
    – James R
    Jul 27, 2019 at 20:39
  • Just so I'm clear. I'm only agreeing that the mixing valve is the culprit and not that they need a cleaning in both baths. You won't be able to see nor repair the damage that matters even if you find debris to remove. And, the other shower may be causing the problem. Replacement of the cartridge in only your shower may just fix the problem halfway if both are failed or the other may fail next week. That's another Plumber charge or trip to a Home Improvement store to do the other shower later.
    – Iggy
    Jul 28, 2019 at 1:50

Sounds like low flow in the hot supply is giving rise to turbulence at some restriction. When you turn on the lavatory tap and it abolishes the squealing, do you turn on both hot and cold taps or just one, and if just one, which one? Turning on the lavatory taps will lower the pressure in the lines.

Maybe you should get a pressure reducer installed at the water service entrance to your house. This would lower the pressure in both the hot and the cold lines. What pressure does the city water provider say that they supply?

What kind of water heater do you have and what is its temperature setting? Setting the temp on the heater at a lower temp will mean that you set the hot faucet in the shower to a higher flow and this may abolish the squealing.

What kind of shower heads are you using? Specifically what is the rated flow from the head? This will be written on the face of the head and it will be something like 2.8 gal/min or 2.0 gpm or 1.4 gpm. It will probably also give it in L/min.

  • Thanks for the reply. When we turn the tap on it's the cold one, although it's a mixer tap, and so it's turned to cold. I've not checked the pressure with our water supplier, I will do though, and see their response. We have a combi boiler, so heats the water as it comes into the house. I've checked and it's set to 5 our of 7, although I think that's only for the radiators. We have it serviced every year, and never had any mention that the heat should be adjusted. Our shower heads don't give any rating that I can see, I'll have a look tomorrow more closely to see if I can find one.
    – James R
    Jul 27, 2019 at 20:46

I had a proper look at this a couple of weeks ago, checking the head, and pipe connections to the wall, and nothing looked amiss. I cleaned the filters, and any loose parts, put them back in, and still had the same problem.

I did however notice by chance when testing it, that if I didn't turn the pressure (or power) tap fully round, it would still give a good flow (pretty much full), and wouldn't have the annoying sound and loss of pressure.

We spoke to our plumber about something unrelated this week, and he mentioned that he'd had a think about our shower, and come up with a theory.The water pressure in our house is high, so when the hot water comes through, it pushes so hard behind the shower, it pushes the cold water back away from the shower in the pipes.

This makes sense, as it would explain the pressure loss, why it takes a while to happen (it takes a while for the hot water to push the cold back), and would explain why turning the power and therefore pressure on the shower fixes the issue.

So we could have an expensive job of fixing our water pressure, but it hasn't caused any other issues, so for now, we'll just continue the cheap solution of only turning the tap halfway.

  • Thanks for answering your question in such detail. If you do learn more, it would be great if you added it here. Oct 14, 2019 at 21:48

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