Hot Topics: New Plumbing Invention or Newbie Plumbing Disaster?

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Never stop innovating. That said, sometimes the old way is the old way because it’s smart and it works. The methods we use for plumbing are kind of ancient, so maybe there’s room for improvement. But before you drill any holes or cut any pipes to implement your new idea, run it up the flagpole and see if the Forum salutes it.

Original Post: Creative? method to combine vanity drain and two water supply lines

awol_OK Member

Please comment on anything wrong with this idea. We have new tile floor and I need to install a new vanity. I am conservative, cheap, innovative, practical.

Diamond bit hole saws are expensive and I don’t want three holes in the new floor. I am planning to run the hot and cold supply lines INSIDE the 2 inch CPVC drain line. Sealing the elbows of the supply, top and bottom with epoxy capable of sealing gravity drain water. Now I can have one hole in the floor and accomplish all three needs. Yes, once in place it will need to be cut top or bottom to replace. No, I won't have a full two inch drain due to the area lost by the two supply lines, but I think it will still drain a vanity. Yes, using CPVC. Please tell me why this is a bad idea!



Highlights from the Thread

mitch17 Group Moderator

I'd wait for Mike (Lawrosa) to chime in but I can't see how that would be code compliant if even a good idea.

Pulpo Member

You need a miracle worker for that one.

ray2047 Group Moderator

Drain line would be 1 ¼-inch or maybe 1 ½-inch. 2 inches is not normal. If plastic they would normally be PVC not CPVC. Water lines are normally run through the wall not the floor. Nothing about your post makes sense. Is this your first plumbing job?

Handyone Forum Topic Moderator

“Please comment on anything wrong with this idea.”

Everything. Sorry. Drain lines are not conduit for passing lines through.

I understand you probably want a clean look inside vanity. The way to accomplish this is with very accurate measurements and use of escutcheon plates to give you leeway.

Many people here can give tips on how best to make accurate cuts if you need it.

If your pipes are outside of walls, you need three holes in floor and cabinet bottom:

- Drain Line
- Hot and Cold Supply Lines

"Straight" shut off valves are normally installed close to bottom of cabinet.

ray2047 Group Moderator

Most drains through the floor were in the past connected with S-traps. S-traps are no longer code compliant. It is better to run them in the wall and use P-traps. While there are ways to put a P-trap on a drain through the floor it isn't going to give it a clean look.

Why aren't your pipes in the wall?

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