I have these water pipes (for hot and cold water) exposed for easy access. There is this tee joint which has been corroding for the past few years. I would like to replace it, but before I call a professional I'd like to assess if this is something I could do myself with the right tools. The problem is I do not have experience with this kind water pipe work, and it is hard to play with the parts and threads with all the piping in active use.

Prior assessments of contractors whom I called for a quote included, among others, suggestion that because of rigidity of the connections the tee joint has to be sawn off.

The water flows from the right. There are two valves to shut off both cold and hot water. In the middle is a mixer, which takes some of the cold water flow. The tee joint is right above it. Pipes on the left lead to final outlets in the apartment.

So the main question is as already stated, is this something I could fix myself? If the answer is yes, what kind of tools would I need? What connections would I need to unscrew and in which order, and in which direction? What addidional replacement parts would I need for this (I have two already purchased)? Would I need to hammer the wall around some of the pipes?overall view

I suspect some of the existing connections have length which can be adjusted - please correct me if I am wrong. close upreplacement partstop view

[EDIT] Extra pictures requested in the comments: top view of hot water meterface of the mixer's knobside closeup of the mixer

[EDIT 2] As a final comment - thank you for all the contributions and suggestions. I would like to add another idea I had (pic attached) that could help alleviate some of the alignment headaches, but I might be jumping the shark with it. enter image description here

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    I would love it if you would explain more. You have unmetered cold water, metered hot water, and you mix them before feeding your fixtures where I assume you feed both the cold and the mixed water and can mix them some more? I have never seen that. What country are you in? What is the source of the hot and cold water? Are they completely independent?
    – jay613
    Aug 27 '21 at 12:10
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    The "mixer" is the white, knob looking thing on the lower T? It can be set to guarantee 100% that no water will escape upwards from the Hot water supply side? i.e. it can be used as a shutoff valve? Can you get us a close up of the end of that mixing valve (showing any labeling that may be there), as well as a close up of the face of the other round device on the lower supply line (which looks a lot like a small meter)?
    – FreeMan
    Aug 27 '21 at 12:11
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    I'd do an experiment. Turn the mixer knob all the way to the - direction. Turn a hot water tap on somewhere in the house and hold a thermometer in the water stream. Wait for the temp to stabilize and make note of it. Next, turn the cold water shutoff to the off position. Repeat the temp test at the same tap. If the two temps are the same, then it would appear that the mixer can fully shut off the cold water. If they're different (and the cold water tap off is hotter), then the mixer will not shut off the cold 100%. If the cold water valve value is hotter, you've done it wrong do over.
    – FreeMan
    Aug 27 '21 at 12:44
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    I would also suggest taking a wire wheel and cleaning up all the corrosion/mineral build up on the outside of all the pipes & fittings. Use a wire brush where you can't get the wheel in. Since this is exposed, that'll make it look nicer, plus, you'll get a better view of exactly what's going on, and it'll make it more obvious more quickly if you've got a leak in the future since you'll see it building up again on nice, clean pipes instead of having to detect additional build up on already messy pipes.
    – FreeMan
    Aug 27 '21 at 13:53
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    I tried to adjust the mixer but the knob wont move. So I did another simpler experiment, which answers how does the mixer work: I shut down cold water and opened one of the taps. The result was no cold water running. This means that flow of cold water to the mixer is unidirectional. Aug 27 '21 at 14:07

Hire a plumber!

This is an easy DIY project for someone with some experience, but by the sound of it not something you should attempt yourself. If you are at the level of experience where you do not know what tools or replacement parts you need, you should hire a professional to do this.

The reason is that with the water shut off, if you discover you are missing a part or if you break something and need to go replace it, your home will be entirely without water until you do. No water do drink, no toilets. You can take steps like filling pots with water and "not flushing" but that only goes so far. How long can your family survive without water? 12 hours? 24? Three days until you learn to fix this and finally get all the right parts?

My approach to DIY is always: Is it possible I will make my home uninhabitable? Will my family need to move to a hotel? If the answer is yes, I hire a professional. You should do that. (The other criteria is "will I probably hurt myself"? But that's not a big factor here).

[ EDIT given new info about independent supplies ]

If you have two independent sources of water and you live by yourself you are in a much better position to attempt this repair. From comments, you have separate cold and hot water supplies and mixer for the hot. If you run into big trouble with the T, you have several options to partially restore water service. Perhaps the mixer can be adjusted just by turning something to shut off the cold side. Perhaps you can disconnect the cold supply to the mixer and just put a cap on there. Perhaps you can remove the mixer and temporarily replace it with a flexible hose connecting the hot supply to the hot manifold. You have a lot of options so you will probably not be stuck entirely without water for days.

Here is a guide to how you should approach this if you choose to try:

With two water supplies you are in better shape to attempt this but the rusty damaged part is connected directly to your cold shutoff valve so if there is not an additional outside shutoff you need to proceed carefully.

  1. Turn off both supplies and also the cold supply outside if there is one.
  2. Disconnect the four cold hoses from the manifold.
  3. Disconnect the mixer from the cold or, if it won’t turn due to corrosion, saw the pipe feeding cold to the mixer and then disconnect the stub from the mixer.
  4. If possible turn the mixer to “only hot” or if not, place a cap on the cold supply side. Turn the hot water back on and check for leaks, then turn it off. You will only use this "hot water only" configuration if you encounter big problems.
  5. With the cold manifold still connected, remove the tee from the cold supply. This is the most precarious step in the process. We keep the manifold connected because it might provide some leverage to turn the tee from the supply valve. If there is no outside shutoff, and you feel like you might damage the cold supply valve, STOP and call a plumber.
  6. Try to remove the tee from the cold manifold. If you cannot, buy a new manifold.
  7. Install the new tee. Connect it to the cold supply and to the mixer. Screw a cap into the cold output of the tee and temporarily turn the cold water back on to look for leaks in your installation so far. Then turn it back off and remove the cap.
  8. Replace the cold manifold and replace the distribution hoses. Turn the cold water on and check for leaks.
  9. Turn the hot water back on, restore the mixer to the desired setting, check for leaks and check the temperature at the taps.

To answer some of your specific questions:

Tools: Two large pipe wrenches for removing and replacing the main fittings and one small pipe wrench or open wrench small enough to fit and remove the four cold hoses. Small hacksaw.


  • Thread tape.
  • If the cold hoses use compression washers (I don’t know), new compression washers.
  • Shutoff caps that will fit the cold output of the tee and the cold input of the mixer.
  • New tee.
  • New bit of pipe to connect the tee to the mixer.
  • Not clear how the tee is connected to the mixer, I think it might use compression couplings, so you'll need a couple of those.

Should you hammer the wall? — No. Maybe I don’t understand this question.

Which way to turn? Practice with those new parts you bought. Everything is the same but it's possible you have some threaded and some compression couplings. I can't tell.

Your biggest problem will be that trying to remove a rusty threaded part without breaking the good parts requires experience to know how hard you can turn and when to stop trying and saw it off instead.

  • Unless I remove the mixer I can switch it not to take in any cold water - this would still give me hot water supply. Not an ideal situation, but since I live by myself I could survive that for a couple of days. Aug 27 '21 at 12:00
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    Having gone down the "oh, this will be simple, I've done this kind of work before" route, then ended up with 3 runs to the store (and I'm 20+ minutes from the closest hardware store) to get the right parts, an hour at the store trying to sort out exactly what part it is that I need this time (and a trip to the bathroom while I'm there because there's no water at home), I have to endorse this answer as opposed to the DIY route which I'd normally encourage.
    – FreeMan
    Aug 27 '21 at 12:00
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    If you live by yourself, fill a few bottles/pots with water to drink and cook, if you have a neighbor who will let you use their toilet and maybe you can go to a gym or public shower if you have to ... yes this could be a great educational rewarding DIY experience. Covid lockdowns might make neighbors and public bathrooms harder to access than before.
    – jay613
    Aug 27 '21 at 12:05
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    Note that the update is full of "may" and "perhaps" - there's no guarantee!
    – FreeMan
    Aug 27 '21 at 12:40
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    Ya I'm getting nervous about this ... realizing the rusty part is connected to what may be the main shutoff .. if there's no outside shutoff this is definitely not DIY!
    – jay613
    Aug 27 '21 at 12:42

You seem to have chosen a brass tee to replace the rusting galvanized tee, and a reducer to reduce the branch size down to half inch. This is the right thing to do.

But you don't have all the parts you will need.

Expect to need to replace the ferrule on that short copper pipe and the nipple and nut at the top end may need replacing too (especially if they are not brass).

To access the rusted tee, you'll need to disconnect all those plastic lines and then unscrew the manifold towards the corner of the room.

To get that copper pipe out of the tee you'll have to undo the union on the outlet of the temperature valve, the nut at the top of the copper pipe, and the union on the left of the water meter. If the ferrule or the nut at the top of the copper is damaged you may need to replace the whole copper pipe and both ferrules.

For reassembly you'll need hemp fiber or Teflon tape to seal the threaded joins to the tee.

So in addition to the parts you have, you should also get a replacement copper pipe and ferrule for both ends and all the hardware needed to connect the top end of the copper pipe to the tee, plus the Teflon tape to seal the threaded joints.


Can you do it yourself, yes.

Are you allowed to do it yourself, maybe, apartments might need professional, depending on your local laws/regulations.

Tools required probably a couple decent adjustable wrenches, a couple pipe wrenches, a hack saw and wire brush, and pipe sealing tape/paste.

Pieces required are all the ones that don't come apart nicely. Quite a few five minute jobs take 5 hours of running around town for extra pieces.

Some screw in pieces sometimes are very hard to unscrew, pieces around the tee, probably the worst.

  • I own the apartment so I am allowed to do quite wide range of modifications. Aug 27 '21 at 12:01
  • When it comes to fitting all the pieces together, is my assumptions that some of the connections have adjustable length (like the one between the tee and the mixer) correct? I suspect that not having such option makes this many times harder. Aug 27 '21 at 12:05
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    They are not really adjustable, except for a tiny amount. The rest of the pipes should be kept in a straight line, because if off centre, leaks are easier to have. If need to adjust one, then need to adjust others as well.
    – crip659
    Aug 27 '21 at 12:16
  • @WojciechMigda there is little to no adjustability in any of these lines. They're all hard copper or steel (looks like you've got a good mix), and they won't bend. You may get some flexibility because of the PEX pipe on the left of the image, but in my view, it could still be difficult to get all the pieces to line up.
    – FreeMan
    Aug 27 '21 at 12:39
  • @FreeMan That sounds like a solid argument against me undertaking this. Aligning everything correctly does no look trivial; the replacement tee I have differs in some length dimensions compared to the rusty one, which I hoped to be able to compensate using some adjustable parts. Aug 27 '21 at 12:44

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