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Shut Off Main Water Supply — Shut Off Water and Drain System

Intermediate

Part of project

How to Rough-In Plumbing for a Bathroom Vanity · Step 2 of 8

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Before starting the repair, locate the main water shut-off valve for the house. This is often found outside, in a basement, or a utility closet. Turn the valve handle clockwise until it is fully closed. To confirm the water supply is off, open a nearby faucet, such as the outdoor hose bib shown in the video, to drain any remaining water from the pipes and verify that the flow has completely stopped.

Goal: Prevent water flow during repair

  • Failing to turn off the main water supply will result in uncontrolled water flow and potential flooding when you remove the cartridge.
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FAQs

How difficult is it to rough-in plumbing for a vanity, and how long should I expect it to take?

This project is rated "intermediate" because it requires precise measurements, proper pipe joining techniques, and an understanding of plumbing codes. For a DIYer with some experience, expect 8-16 hours of work, depending on existing wall access and any unforeseen issues. Costs can range from $150-$300 for materials, assuming you already own basic tools.

What are the most crucial safety precautions I should take when roughing-in plumbing?

Always shut off the main water supply before cutting into existing lines to prevent flooding. Wear appropriate personal protective equipment (PPE) like safety glasses, gloves, and hearing protection, especially when using power tools like drills and hole saws. Be mindful of electrical wires inside walls when drilling or cutting.

The guide mentions PEX for supply lines; can I use copper or CPVC instead, and what are the pros of PEX?

While copper and CPVC are alternatives, PEX is often preferred for DIY projects due to its flexibility, ease of installation (fewer fittings, no soldering), and resistance to freezing. However, PEX requires specific crimp or expansion tools. If you're comfortable with soldering, copper is a durable choice, and CPVC offers a rigid, solvent-weld option.

What are the most common mistakes DIYers make when roughing-in a vanity's drain and supply lines?

A common mistake is incorrect drain slope, leading to clogs – ensure a 1/4 inch per foot slope for DWV lines. Another error is misplacing supply stub-outs, making fixture installation difficult; always double-check vanity and sink specifications. Also, failing to properly prime and cement PVC joints can cause leaks.

Shut Off Main Water Supply — How to Rough-In Plumbing for a Bathroom Vanity (Step 2, Video 1) | Stesso