Replacing old under-sink shutoff valves
Old multi-turn shutoffs under sinks and toilets often seize or drip when you need them.
Updated · 3 min read
The quick version
Angle stops are the small valves feeding each faucet and toilet. Old multi-turn ones seize or leak at the stem after years of sitting open. Replacing them with quarter-turn valves and new supply lines makes every later repair simpler.
Sections
What angle stops do
Every sink and toilet should have its own shutoff. They let you stop water to one fixture instead of the whole house.
In San Gabriel's older homes, some fixtures have no stop at all, and others have brass multi-turn valves that have not been closed in decades.
Test them before you need them
Turn each stop clockwise slowly, then back. If it will not move, does not stop the flow, or starts dripping at the stem, it needs replacement.
Supply lines too
Older installs use rigid chrome tubes or rubber hoses. Rubber hoses crack and burst with age; braided stainless lines are the usual replacement.
Compression, sweat and threaded
How a new stop attaches depends on the pipe coming out of the wall. Copper stubs take a compression or soldered valve; galvanized nipples take a threaded valve and are often replaced at the same time.
If the pipe stub is corroded inside the wall, it may need a short section cut back to sound pipe.
Questions we hear
Do I have to shut off the whole house to change a stop?
Yes, unless the stop is downstream of another valve that works.
Can I replace just the washer in an old stop?
Some multi-turn stops can be rebuilt, but a replacement usually costs about the same effort and lasts longer.
What length supply line do I need?
Measure from the stop to the faucet or toilet inlet and add a little slack. Common lengths fit most sinks.