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Thread: Water pressure drop after remodel?

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    DIY Junior Member stanh's Avatar
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    Default Water pressure drop after remodel?

    We had a contractor do a bathroom remodel and we are finding that the water pressure from the fixtures have dropped. I noticed that the contractor used 3/8 inch lines for the faucet (we had provided 1/2 which should have been used). In addition, we have a much larger shower head with more jets post remodel. Could these things cause the issues we are seeing?

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    Retired Defense Industry Engineer jadnashua's Avatar
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    If your old stuff was really old, you may be experiencing the federally mandated flow restriction verses a drop in pressure. All new showerheads are limited to a maximum of 2.5 gpm and a lav faucet about half of that. The only things left unrestricted in a house are typically things like the tub filler, hose bibs, washing machine fillers, and typical stuff like that where you are expected to get lots of water as fast as you can. The more daily use things are all now flow restriced (for things like sinks and showers).
    Jim DeBruycker
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    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Junior Member stanh's Avatar
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    Thanks for the quick responses. The stuff was older (well, in my mind). My guess is that it was done in the late 80's or early 90's - the one exception was that the shower head was a newer (2.5 gph) model. However, it is smaller and has about half as many jets.

    Also, in response to the other questions, this is what I can tell you.

    The contractor used the existing lines. They are copper. I was able to find one of the supplys that is used for the shower. It is a 5/8 line (copper). From what I recall, all lines in the wall before it was closed up were also 5/8.

    The faucet lines are not the braided flexible lines - rather chrome plated copper lines that need to be bent.

    Thanks again for the help.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    5/8" OD = 1/2" ID copper. The brand and model of a showerhead can make a huge difference in the feel of a shower. If the solid risers to the faucet are 3/8", it should be fine. But, most of the faucets these days come with lines attached, so sort of surprised they used solid ones. Solid can last longer, and may look better if exposed, but if inside a vanity, kind of a waste IMHO. They had already started some of the flow restrictions by the late 80's.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    Retired Defense Industry Engineer jadnashua's Avatar
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    When everything is on in the shower, what is the rated gpm? As mentioned, depending on what that is, it may have dictated a larger supply and valve.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Junior Member stanh's Avatar
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    Not sure if this answers the question, but, the shower head is a 2.5 gallon per minute head. Also, for the sink, we used solid lines because it is for a pedestal sink and they are to some degree exposed.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    If that shower head is the only thing (not a bunch of body sprays, etc. that could be on also), any 1/2" valve should be more than enough volume to provide full output of the shower. One thing you could do is remove the head, take a big bucket and measure how much water comes out in a minute (or less, then adjust to figure out the gpm). If it is more than the 2.5g, then the only way to make it better is to buy a different shower head. If it is less, then something's wrong...some valves have filter screens on their inputs. If these are partially plugged, it could restrict the overall volume available. Note, pressure, with no flow, is the same whether you have a soda straw sized pipe or a fire hose. Obviously, you can maintain the pressure to more things with the fire hose than you can with a soda straw. A 1/2" line can safely supply about 5-6gpm at normal house pressure (on each side - hot and cold). So, the total volume will change some based on the mix of hot and cold you have to get your desired temp. One thing about say a tankless system where you've got it adjusted so all hot is your desired shower temp...your total volume will be less since you can't add some volume from the cold side to temper it to your desired temperature.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    Moderator & Master Plumber hj's Avatar
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    3/8" water supplies to the faucets will supply a lot more water than the faucets can use. The openings in the faucet itself may only be 1/4" or less. If you had given me 1/2" supply lines, I would have told you to take them back and get a refund on your money, because I would not have used them.

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