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My house in in western New York state. I'm trying to deal with the hack job that the previous owner or flipper did on my house with respect to the water supply lines in the kitchen (hot to sink, cold to sink, hot to dishwasher).

I could use some input on priorities, parts, tools, and best practices.

My house was built a long time ago (city thinks 1900-ish), and building codes have changed since then. The basic situation is the following. The ground floor is held up underneath by metal support columns, main wooden beams, and wooden support joists. I don't know what the sub floor's made of, but above that the floor is covered in grey vinyl designed to look like wood. The water input is a single 1/2 inch Pex cold supply line that splits to go a gas water heater, the ground floor kitchen, and the second floor bathroom. The hot water comes out of the gas water heater, splits once to go to the kitchen and to the second floor bathroom, and then splits again at the kitchen (sink and dishwasher). Hence all of the supply lines have to go through the floor between the basement and the ground floor.

The kitchen supply lines were installed to come through the floor instead of through the wall, so right now the quarter-turn shut-off valves are simply hanging out on top of the vertical Pex tubing that's sticking up out of the floor for the sink (hot, cold), and the dishwasher. I'm not in a position to re-thread them through the wall. It's winter, and the wall is an outside wall.

In addition to all of this the sink has an S trap rather than a P trap, so the sink drains down a vertical pipe into the basement rather than horizontally into a drain pipe in the wall. There's no main house stack so the sink drain needs an air admittance valve. Unfortunately, that was put in the basement well below the level of the sink trap, so moving it involves cutting ans rejoining already-existing PVC.

So far as I can tell there exist three main things on the list of kitchen plumbing that need taking care of under the kitchen sink.

  1. Protection at the main and sub floor for the tubing that comes through it.
  2. Some sort of flanges to secure and support the Pex tubing (and the quarter turn valves) after it comes through the floor (in three places).
  3. Replace the S-trap with a proper P trap and move the air admittance valve during this process.

As an additional note, none of these things is causing issues at the moment, and in the time we've lived here (about eight months) there have not been problems with any of the things mentioned here. I understand that there are risks involved with everything discussed. The S trap could lose its water seal, a sewage backup could cause the AAV to pump out sewage instead of admit air, the Pex could break somehow at the floor, and the Pex could break above the floor. All of those are possibilities.

The main questions here, then are:

  1. What's the priority list on these issues? What should I correct first, and what can wait until later?
  2. What of this is something that I can reasonably do myself (as a non-expert), and what is best left to a professional?
  3. What materials and tools would I need to make the necessary upgrades?

Below is a picture of what the plumbing under my kitchen sink looks like. The clearish tube is the drain for the dishwasher.

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    If you ever think of putting pipes in an outside wall, have someone wack you a few times. Would probably do the S trap first. Looks like it can be done by hand only, except for maybe cutting new pipes to size. The plex pipes are in a cabinet so it is not like you will be tripping on them to break them. Adding a flange in time should be enough.
    – crip659
    Dec 28, 2022 at 17:22
  • 2
    Your dishwasher drain hose (a) should be positioned up as far as possible, (b) should be shorter. Basically it should come out of the side panel, go immediately up as far as possible (i.e., just to the underside of the counter) and then go only downward (not a roller coaster loop...) to the drain. Which means chopping a foot or two off of it. Dec 28, 2022 at 17:24
  • The suggestions above are right on target! In addition since there is no vent stack you probably will want to add an AAV (if within code) with a sanitary tee on top of the stack drain. Get rid of the top bend coming out of the P trap and run a horizontal piece directly into the sanitary tee with the AAV above it. While you are at it bring the tail piece coming out of the sink drain on the right to vertical alignment with the drain stub. Right now it's prone to leaking.
    – HoneyDo
    Dec 28, 2022 at 20:12
  • first? first would be to fix that dishwasher hose, it should enter the drain above the trap. and should not have any dips in it. it look like you have enough parts there, they just need to be swapped around a bit,
    – Jasen
    Dec 29, 2022 at 1:34
  • "Swapped around" means what? Wouldn't dealing with the dishwasher hose just involve cutting it like manassehkatz-Moving 2 Codidact said earlier?
    – THill3
    Dec 29, 2022 at 16:30

1 Answer 1

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How best to brig old Pex water lines up to code / safety

Old??? Those look fresher than Febreeze.

I'm trying to deal with the hack job that the previous owner or flipper did on my house with respect to the water supply lines in the kitchen (hot to sink, cold to sink, hot to dishwasher).

I've seen and live with considerably worse.

The water input is a single 1/2 inch Pex cold supply line

I would get quote to upgrade this to a 3/4" or 1" line in the spring/summer time. Standard water heater inlet/outlet is 3/4".

The kitchen supply lines were installed to come through the floor instead of through the wall

Well, frozen water pipes in the wall are a considerably worse issue than ones that flow through the floor.

so right now the quarter-turn shut-off valves are simply hanging out on top of the vertical Pex tubing that's sticking up out of the floor for the sink (hot, cold), and the dishwasher.

Buy some PEX pipe floor joist insulators/bushings to protect them from damage. Install an escutcheon plate to make it less ugly.

I'm not in a position to re-thread them through the wall. It's winter, and the wall is an outside wall.

Yeah, don't. Unless you wish to give yourself frozen pipe issues.

In addition to all of this the sink has an S trap rather than a P trap, so the sink drains down a vertical pipe into the basement rather than horizontally into a drain pipe in the wall.

All P-traps are S-traps anyways unless they are vented.

There's no main house stack so the sink drain needs an air admittance valve. Unfortunately, that was put in the basement well below the level of the sink trap, so moving it involves cutting ans rejoining already-existing PVC.

This is a "meh" situation at best. You'll get some gurgling so just make sure to run a little bit of water after you're done using the sink to avoid a dry trap.

What's the priority list on these issues? What should I correct first, and what can wait until later?

  1. PEX bushings
  2. Upgrade the supply size entering the house
  3. P-trap with venting

What of this is something that I can reasonably do myself (as a non-expert), and what is best left to a professional?

  1. PEX bushings - You
  2. Upgrade the supply size entering the house - Pro
  3. P-trap with venting - Pro
    • You seem gung-ho on code compliance and many localities do not approve of AAVs even if they are readily available in stores

What materials and tools would I need to make the necessary upgrades?

None, get the PEX bushings and call a pro.

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  • I really appreciate you addressing the points in my post and being clear about what you're addressing.
    – THill3
    Dec 29, 2022 at 16:22
  • Turns out I was wrong about the supply line size. It really is 3/4". Can anyone help me with the exact names of the things that I need? There are a lot of different kinds of "bushing"s, and "insulation" could mean just foam to wraparound the pex line
    – THill3
    Dec 29, 2022 at 16:28
  • @THill3 You're welcome, glad I was able to coherently address the myriad of concerns and thoughts. Sorry but nowhere in my answer did I specify insulation, rather "insulator" like these. I mean there's not much reason for foam to be a bad choice, your goal is to protect the plastic from rubbing against the wood. Albeit, foam would wear out quickly if you keep carelessly hitting your pipes with stuff.
    – MonkeyZeus
    Dec 29, 2022 at 16:33

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