I just installed a new tub fixture set: enter image description here

There are two controls - one for temperature and one for volume. The large handle is volume.

When the diverter valve is engaged the shower sprays properly and no water comes from the spout: enter image description here

But if I disengage the diverter and run the water at full pressure, the spout flows but there is still a slow shower from the shower head: enter image description here enter image description here

However, if I reduce volume enough: enter image description here (note the angle of the volume control) the shower stops dripping: enter image description here

Is something wrong with my installation, or am I right in suspecting that I simply have too much water pressure in my house?

I've checked all the plumbing from behind (the wall behind the tub is open) - there are no leaks.

  • No sounds like you've got the idea just to much pressure and the divertor spout is sending some water up to the shower, u could try putting a water restrictor on the shower hose to stop this happening if it hasn't got one already.
    – UNECS
    Nov 18, 2012 at 4:05
  • is the diverter valve also a Delta? I recognize the spray head, have two exactly like that. Nov 18, 2012 at 10:35
  • Yes the whole assembly is Delta. Nov 18, 2012 at 11:14
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    That delta volume/temp dual control is a bear to assemble and calibrate. I bet one of the O-rings got turned over or is not seated properly. Nov 18, 2012 at 18:46
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    This can happen regardless of pressure. It is an issue of more available volume than the tub spout can handle, so the shower ends up being a sort of overflow device. Since high pressure increases volume though, it could still indirectly be pressure related.
    – bcworkz
    Nov 18, 2012 at 21:50

6 Answers 6


What did you use to connect your tub spout?

I plumbed my bathroom with Pex and was heavily cautioned NOT to use Pex to run from the main valve to the tub spout because it would create exactly the issue your describing.

Since the inner diameter of Pex is slightly less than regular copper (or threaded brass fittings, which is what I used) it will create a slight flow restriction to the tub spout and (inadvertently) divert it to the shower head.

Just a thought...

  • I used PEX. I'd never heard that before... Well ... that's fixable. :) Dec 1, 2012 at 10:53
  • Any update? Did that resolve the issue?
    – euphonek
    Feb 28, 2013 at 20:34
  • I haven't gotten back to it yet - the wall behind the tub is still open and renovations are on hold pending rebuilding our project funds. :) Feb 28, 2013 at 21:30
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    I FINALLY replaced the line between the mixer and the spout with copper. Works perfectly now. (Don't ask why it took so long - 2013 was a very bad year for us...) Sep 13, 2014 at 19:57
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    wow. I was just about to ask this very question about an American Standard setup when I came across this answer. I plumbed it in pex as well. But, even worse, I ended up with the tub faucet at a 90 deg. angle and so I just cut the pex and put an additional elbow in going from the valve to the tub faucet. That's when it started coming out the shower when it's on all the way. Makes perfect sense now. I already had restricted flow and then added an elbow to boot.
    – maplemale
    Apr 24, 2015 at 18:02

It seems to me that it boils down to the basics... you have a certain volume of water at a certain pressure. If the diverter is fully open, and there is more water coming through than it can handle, then there is overflow going to the shower.

The water pressure can't be more than what is available coming in, so that should be regulated for the whole house; if it's too high, valves could fail elsewhere. If it's correct, then this can't really be the problem (directly).

So, it must be a matter of pipe sizes or diverter valve capacity. There must either be an obstruction at or after the diverter valve, or the pipe going to the shower is too small and fills up, so to speak. If the pipe going to the shower head was bigger, it would act as a reservoir and take more water before it overflows out the shower head.

It may be that there is simply too much water coming to the shower, and a flow restrictor leading to the valves, or limiter on the valves is needed. I don't know if the valves have a way to limit the water. The main question would be whether there is lots of water coming out of both the shower head and the tub outlet when the valve is at the setting that does not come out of the shower head when it shouldn't.

Sorry this isn't exactly a full answer, but it's too much to put in a comment, and I thought it might be helpful for troubleshooting the problem.

  • What is the proper level of residential water pressure? Nov 20, 2012 at 18:28
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    Oh - disagree on "pipe to shower is too small" - no matter how big the pipe, if ALL the water isn't getting out of the tub spout as it becomes available, the pipe will fill up. Nov 20, 2012 at 18:29
  • I've heard 80 psi for the maximum pressure a lot. But if any devices (ie, washing machines, etc) have valves that are rated lower, then that may be too high. As for the pipe to shower part, it may or may not be an issue. You make a good point, but it would take more pressure for a bigger pipe, and also the weight of the water would create more back pressure. Anyway, it's part of the equation, and not really meant to be a real solution, just added for completeness. Nov 20, 2012 at 18:38
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    The weight of the water on a 3' rise in a 1/2" diameter pipe is so negligible as to not have any noticeable impact on the total pressure required to make the water overflow. Nov 20, 2012 at 18:48
  • You are probably right; troubleshooting a problem (something I'm pretty good at, in general) is often a matter of eliminating possibilities until there is only one or a manageable few possibilities, then checking those. In my experience, it's best to consider all possibilities first, as sometimes what I thought to be impossible turns out to be the answer. Nov 20, 2012 at 19:14

It seems to me that you have cartridge problem. Replace it and you would be fine. There is nothing wrong with your pressure or your plumbing. And Oh, Pex is fine.


Problem solved

Details about this solution are HEREMake a Loop

  • Slick! Looks like that would work but only if you get that loop high enough for the amount of pressure that's backing up. Great idea though! Dec 22, 2018 at 1:01

The volume of water to the tub spout can be too high creating back pressure which leads to water dripping or pouring out of the shower head. To solve this, try using 1/2" brass pipe fittings from the control to the tub spout only. This increased diameter of pipe will allow full flow and prevent any back pressure. I have done this numerous times on all types of controls and it works every time.

Decreasing the water pressure at the valve can, and likely will, cause frustration because of the noticeable lack of pressure.

Good luck.


I had the same problem today and after looking into the pipe connection in the wall that connects the faucet, I noticed that a rubber gasket on the 90 degree elbow was damaged and was prohibiting the proper flow of water. Might be something to check out.

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