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Prepare the Under-Sink Plumbing — Drain the Line

Beginner3 hours

Part of project

How to Replace a Leaky Angle Stop (Shutoff Valve) Under Your Sink · Step 3 of 9

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In this video

Prepare the existing plumbing under the sink for the modification. The most critical part of this step is to shut off the main water supply to your house. Once the water is off, open the cold water tap on the sink to relieve any pressure and drain remaining water from the line. Place your towel under the cold water shut-off valve. Using an adjustable wrench, carefully loosen and remove the existing flexible supply line that connects the shut-off valve to the sink's faucet.

Goal: Isolate Water Supply and Disconnect Sink Line

  • Confirm the water is completely shut off before disconnecting any lines. Failure to do so will cause significant water damage.

Used in this video

  • Adjustable wrenchLoosening the nut on the sink supply line.
  • TowelCatching residual water.
9.0K views12210 minutes
This Old House

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FAQs

What's the single most important safety step to take before I even touch the leaky angle stop?

The most critical step is to shut off the main water supply to your home. This prevents potential flooding and ensures a safe working environment. Always confirm the water is off by testing a nearby faucet before proceeding with any work.

The project is listed as 'beginner' difficulty, but 3 hours seems long for a valve. Is it really that involved?

While replacing an angle stop is beginner-friendly, the 3-hour estimate accounts for prep work like gathering tools, draining lines, dealing with potential seized parts, and thorough leak testing. Taking your time ensures a proper, leak-free installation, so don't rush the process.

I see "Adjustable Wrench" and "Tongue and Groove Pliers" listed. Are these specific tools essential, or can I get by with a generic wrench set?

Yes, these specific tools are highly recommended. An adjustable wrench helps securely tighten the compression nut on the new valve without stripping it, while tongue and groove pliers (like Channellock) provide a strong grip for holding the valve or pipe steady. Using the correct tools prevents damage and ensures a tight, leak-free connection.

This project specifically mentions installing a "compression-style valve." Are there other types of angle stops, and why is this type recommended for a DIYer?

Yes, other types include soldered (sweat) and push-to-connect (SharkBite) valves. Compression-style valves are ideal for DIYers because they create a watertight seal by compressing a ferrule onto the pipe, requiring only basic hand tools and no specialized skills like soldering, making them relatively easy to install.

Transcript
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one go here. By that need to be pretty tight. And this will go into the middle. So this is what it's look under the sink. Sorry if the light is not enough. So I have already taken out the. So before you do this, you'll have to shut off the main water supply. So I and then have a towel underneath just in case water spills out. So I've taken out the hose from this pipe. So this will go out here and then this will go under out

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