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I have a very old house (built in 1903) with very old and corroded pipes. Because of the corrosion, the hot water pressure is fairly low (mostly in the shower) but cold water pressure is okay. I’m wondering if it would be an okay idea to switch the cold and hot water lines right after the water heater. I think This would drop the cold water pressure which I don’t mind. I know I’ll need to replace all the piping eventually but I’ll probably be selling in the relative near future.

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    Why would you not replace the pipes? With a little learning it's not difficult and not much more work than switching them. .
    – isherwood
    Apr 16, 2021 at 13:10
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    With the newer plumbing fittings, like push to connect, replacing pipes can be as easy as a putting together a Lego set. Do you really want to drink water from those old pipes?
    – crip659
    Apr 16, 2021 at 13:18
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    Odds are good that a home inspection will flag the low/mismatched water flow and you'll have to repair it (possibly paying someone else to do so) right before you move out. May as well do it now and get to enjoy a good water flow until you move out.
    – FreeMan
    Apr 16, 2021 at 13:22
  • @FreeMan It depends on the buyer. I bought a home with this exact problem 5 years ago. I've replaced all the pipes with PEX about 2 years ago. You only have to fix it if you want to sell to a specific buyer or do not want to get low-balled. In retrospect, I should have low-balled by at least 15% but live and learn.
    – MonkeyZeus
    Apr 16, 2021 at 13:42
  • @crip659 push-to-connect is not compatible with galvanized piping. You would need to properly transition at a threaded joint.
    – MonkeyZeus
    Apr 16, 2021 at 13:44

2 Answers 2

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Your question boils down to "please validate my wonky idea" and I will absolutely NOT.

Yes, you can do it but you shouldn't. At best your proposal is something that would be done in a super emergency situation.


You can switch the hot and cold lines at the tank but that would really be quite an obtuse solution. So now your cold valve gives hot water and the hot valve gives cold water? Good luck getting the proper temperature from your shower if you have an anti-scald valve installed.

Sounds like a surefire way to deter the average buyers and lower your home's value.

I think you will find that by the time you've acquired the right tools to perform a wonky cutover then the cost of materials to just do things properly is insignificant.

PEX has made plumbing so easy that it's almost hard to screw up.

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    Despite my comment on the OP, I agree 100%. +1
    – FreeMan
    Apr 16, 2021 at 14:10
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No!

This would work fine for your sinks, though anyone who visits would get confused because they would assume "hot on the left, cold on the right". (I learned that years ago from an HVAC supplier who didn't think much of ordinary plumbers - all they need to know is "hot on the left, cold on the right, #()$@(#$% runs downhill". But I digress.)

But it would not work for:

  • Washers - though there you can easily swap the connections.
  • Dishwashers - normally plumbed (US) to only hot. If connected to cold they would either not work well at all or spend a huge amount on electricity heating water (e.g., from 50 to 140 instead from 120 to 140)
  • Toilets - always plumbed to only cold. They would waste a huge amount of energy using hot water.
  • Outside faucets - not sure if you use them much, but if you do, I'm not sure your plants will enjoy a hot bath.
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    Upvote for pointing out all of the downstream effects like the washing machine, toilet, spigot, etc...
    – MonkeyZeus
    Apr 16, 2021 at 14:16
  • "downstream" quite literally here. Apr 16, 2021 at 14:18
  • dittos on that! Great answer pointing out all the ramifications of doing this. To the OP: "Get 'er done and like Freeman said, enjoy your new plumbing while you're still there . Apr 16, 2021 at 14:21
  • I know this is a DIY site but, there are companies in my neck of the woods (PNW) that specialize in re-piping older homes, claiming they can get the work done a just a few days.... Depending upon the skills of the OP and the layout of the plumbing in the house, it could be a big job. There are probably companies where the OP resides that offer similar services. It might be better to call a pro and write a check. Apr 16, 2021 at 14:26
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    @GeorgeAnderson OP hasn't stated their skill level nor budget. Given their proposal I can only assume they're trying to save a dime and do it themselves because I am sure that a plumber would have a hard time keeping a straight face if a client requested such a switchover. To re-plumb an open-basement house would easily run $3,000 or more; and that doesn't even include doing the upstairs which would require opening up walls. Writing a check which is bound to bounce does little good for either party.
    – MonkeyZeus
    Apr 16, 2021 at 14:33

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