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Positioning the Water Supply — Locate and Mark Water Supply Lines

Beginner3 hours

Part of project

How to Measure Bathroom Plumbing Rough-In Dimensions for a New Vanity · Step 5 of 6

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In this video

This final step details the rough-in for the toilet's water supply line. The instructor explains the standard placement for the water line stub-out. Typically, the water supply line should be located 6 inches to the left of the toilet drain's center line. This positioning provides ample room for the flexible supply line to connect from the angle stop (shut-off valve) to the toilet tank without being cramped or visible from the front. The height of the stub-out is also important; it must be high enough to clear the top of the baseboard trim. It's crucial to check with the contractor about the planned baseboard height to avoid conflicts. The video shows two types of water supply stub-outs: a copper pipe stub-out, often used to accommodate specific decorative finishes on the angle stop, and a more common PEX pipe stub-out. Both are secured within the wall framing to provide a stable connection point for the final plumbing.

Goal: Plumbing Pipes Installation

  • Standard placement for the water supply is 6 inches to the left of the toilet's center line and a few inches above the planned baseboard height.
  • Always confirm the baseboard height with the builder or contractor to ensure your water supply stub-out is not too low.

Used in this video

  • Pipe Bracket/Support (brand: Unknown, Pipe Hanger Type: Strap hanger) — Securing the water supply pipe within the wall cavity to prevent movement.
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FAQs

Is this project genuinely beginner-friendly, and can I expect to complete the measuring process within the estimated 3 hours?

Yes, this project is well-suited for beginners as it primarily involves careful measuring and marking, not actual plumbing installation. The 3-hour estimate is realistic, assuming you have all your tools and the new vanity's specifications readily available. Accuracy is more important than speed for this step.

Do I need the specific brand-name tape measures listed, or can I use a standard measuring tape and level?

While specific brands are listed for tools, any standard, accurate 25 ft. tape measure and a reliable 2-foot level will work perfectly. The critical factor is ensuring your tools are in good working order and provide clear, precise readings for accurate marking on the wall.

What are the most critical measurements to double-check to avoid costly errors during the rough-in process?

The most critical measurements are the vanity's centerline, the height and horizontal spacing of the drain pipe, and the hot/cold supply lines. Always double-check these against your new vanity's internal dimensions, especially where the sink basin, P-trap, and supply lines will connect, to ensure everything fits without obstruction.

Before marking the wall, should I take any precautions regarding existing pipes or electrical wiring that might be behind the drywall?

While you are only marking the wall, it's a good practice to use a stud finder with AC detection to identify potential electrical lines or hidden studs. This awareness can help you avoid marking directly over sensitive areas, which is beneficial if you later need to cut into the wall for actual plumbing work.

Transcript
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We want to make sure that we've used non corrosive screws to secure it to whatever sub floor or concrete that is holding it down. Water supply for the toilet. Of course, we talked about the drain fitting for it and we got the water coming into it. Again, water typically will come out in the wall like this. Check the base board height. There's a base board is the is the trim board that goes along the floor coming up the wall. And you definitely want to check with a builder or a contractor about what the base board height is going to be. So you can have it come out in a place that's pretty comfortable for the trim guy and it's something that looks really good. You don't want the top of the base board to come right along here to where the pipe and even the decorative beauty ring that comes out is going to run into. So we'll one thing you definitely want to do is check the base board height. What contractors what they'll do is if the toilet stub out is at a place where it's a little bit going to be a little bit funny to trim around. They'll put around some blocking that goes up and make it nice and decorative. So keep in mind the base board height and adjust the height of this stub out accordingly. Another measurement to keep note of is six inches to the left of center of the flange. Just picture this straight line right here coming down this center line for the flange typically you'll want to go from that center line six inches over which makes it pretty comfortable for when we go and set the toilet and the supply line coming up on the left side of the toilet as you're facing it. It's a really comfortable spot to be able to put the stop valve and go up into the toilet for the water supply. The next slide we've got a pecs stub out and this one we had a copper stub out you can see here it's made it's made out of copper and it's got a pecs a connection there. The reason a lot of times what guys will do is when they're used to copper stub out is to accommodate for a specific kind of angle stop which is the valve behind the toilet which will show you in one of the next videos. But a lot of times they'll want that to be somewhat of a different color and so they make those more in a fitting that goes on copper instead of just pecs to be able to make that make this connection to make it look good that way. But here's another toilet supply was just pecs stubing out for just a regular pecs angle stop so there is a pretty good look at the rough end for a toilet.

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