Water Shutoff & Line Isolation: the full procedure

Locate and operate the correct shutoff so water is safely isolated before any line is opened, then restored without damage.

• Applies to: Plumber or apprentice before disconnecting any water line.
• Frequency: Every job that opens a pressurized line.
• Scope: Covers locating, operating, and restoring water at fixture, branch, and main shutoffs. Does NOT cover utility-owned curb/street valves or any gas shutoff, which defer to the water utility, a licensed plumber, and the business safety plan.

What you need

• Flashlight
• Meter / curb key (utility-permitting only)
• Valve wrench / pliers
• Towels and bucket
• Job ticket for noting valve locations

The procedure, step by step

1. Identify the smallest isolation point first — Look for a fixture stop or branch valve before reaching for the main. Isolate only as much of the house as the job requires.
2. Locate the main shutoff if needed — Check where the supply enters the home: basement, crawlspace, garage, mechanical room, or near the water heater. Note the valve type (gate or ball).
3. Operate the valve gently — Turn a gate valve fully clockwise or set a ball valve handle perpendicular to the pipe. Do not force a stiff or corroded valve; if it will not move, stop and reassess.
4. Do not touch utility-owned valves — The curb or street valve belongs to the water utility. Operating it is the utility’s or a licensed plumber’s call, not a default field step.
5. Confirm the line is dead — Open a downstream faucet and verify flow stops to zero. Never cut into a line you have not confirmed is depressurized.
6. Note the valve location on the ticket — Record where the working shutoff is so the next visit is faster and the customer knows. Photograph it if helpful.
7. Restore water slowly and bleed air — Reopen the valve gradually, then open hot and cold faucets one at a time until air stops, then close them. Sudden full pressure can cause leaks or water hammer.
8. Verify no leaks at the shutoff itself — A valve that was hard to operate can weep after use. Check the valve stem and packing once water is restored.

Quality check before you finish

• Smallest necessary isolation point used
• Main shutoff located and valve type identified
• Valve operated gently, not forced
• Utility curb/street valve left to the utility or licensed plumber
• Line confirmed dead before cutting
• Valve location noted on the ticket
• Water restored slowly, air bled, valve checked for weeping

This is a free, source-anchored standard operating procedure (SOP) you can print and hand to staff. It documents the work sequence for a Plumbing business — not safety or regulatory rulings, which defer to the cited authorities, the applicable code, and your own health-and-safety plan. Open the tool above to print it, toggle ink-saver, or (with a free ToolFluency Business account) edit it to match your own workflow.

Sources

• Water utility guidance (e.g., WSSC Water main valve) (wsscwater.com)
• United Association (UA) plumbing training standards (ua.org)
• Family Handyman (shutoff valve guidance) (familyhandyman.com)