How would you isolate a single fixture without shutting down the entire cold water supply?

• A. Install or use a dedicated isolation valve on the branch feeding that fixture or a service valve near the fixture
• B. Shut off the main supply
• C. Remove the fixture
• D. Install a water softener

Answer: (A)

To isolate a single fixture without shutting down the whole cold water supply, you use a dedicated isolation valve on the branch feeding that fixture or a service valve located near the fixture. When you close this valve, water to that specific fixture stops while the rest of the cold-water system keeps supplying other outlets. This is the controlled way to perform repairs or replacements without affecting the entire building’s water, which is why it’s preferred over shutting off the main supply. Removing the fixture is unnecessary for isolation, and a water softener has nothing to do with shutting off or isolating a line.