I hope someone can help because I'm truly lost here since I'm not a plumber.

We just had our house built and it was completed just 3 months ago. We have a 50 gallon electric water heater and it seems to be functioning as it should.

Our sinks, toilets and children's shower function properly as does the dishwasher and pot filler.

We have a larger shower in the master bathroom that is not doing so great. This shower has 2 separate shower heads on opposite walls and a rain head in the middle. When I run one shower head the flow is great but if I use both shower heads or one shower head and the rain head then my flow is bad. The shower has a 3 way diverter. The plumbing was done entirely with PEX and I believe 1/2" was used.

I called a couple of plumbers that I know and both told me similar things that are far beyond the scope of my comprehension. I was told that the inlet port could be too small; the plumber may not have put in some sort of balancing loop and finally that the size of my feeder line may be too small and may need to be replaced with a 3/4" line. The only way I would know this for sure is to tear into my new wall and I really don't want to do that. Is there an alternative to identifying the cause of this issue? Could I not simply remove my shower head screw on a pressure gauge and measure from that point?

Please help...I'm pretty desperate here.

Thanks and sorry to be so long winded, Mike and Jennifer

  • I'm struggling to imagine how one in such a fortunate situation could ever be described as "desperate". Perspective, my friend. :) Half-inch pipe with decent pressure should be adequate (if not stellar). I suspect the valving or the heads first, as a less destructive approach.
    – isherwood
    Commented Sep 13, 2016 at 15:14

1 Answer 1


You have 3 shower heads on 1, 1/2" supply line The demand is higher than the 1/2" can supply. The size of the valves also makes a difference with high flow shower heads. Both the supply line and possibly the valve will need to be increased in size for full pressure with all 3 heads turned on. A booster pump or increase in pressure may be another option.

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