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Isolate House Plumbing — Shut Off Main Water Supply

Beginner3 hours

Part of project

How to Replace a Leaky Angle Stop (Shutoff Valve) Under Your Sink · Step 2 of 9

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In this video

Locate the main water shutoff valve for the house. This is often found on an exterior wall where the water service line enters the house. Turn the valve completely off to stop water flow into the house's plumbing system.

Goal: Determine if Leak is Inside or Outside the House

Used in this video

  • Wrench (Wrench_Type: Pipe Wrench) · optional — Turning the main shutoff valve if it is too stiff to turn by hand.
26.4K views5 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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Next thing we're always going to do is see if there's a shut off at the house. If there is a shut off at the house, we're going to shut it off and then we're going to go back to the meter to see if it is still running.

Auto-generated transcript. May contain errors.