If you need to make a plumbing repair to your bathroom sink, you will need to turn off the water to that sink prior to initiating the repair. Bathroom sinks have shut-off valves located under the sink. You turn off the water to the sink by closing the shut-off valve to the sink.
Step 1
Find the shutoff valves located on the pipe below your bathroom sink. If you have a cabinet under your sink, look inside the cabinet to find the shut-off valves. Most sinks have two shut-off valves, one for hot water and one for cold water.
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Step 2
Close the shut-off valves by rotating the knob in a clockwise position. Use your hand to tighten the shut-off valve. You don't want to over-tighten or you could damage the shut-off valve.
Step 3
Turn on the hot and cold water on the faucet attached to your bathroom sink. Allow any water that was stuck in the pipe between the faucet and the shut-off valve to drain out.
Tip
It is also possible to turn off water to a bathroom sink, by shutting off all water to your house. The water shut-off valve is normally located outside your house. If you don't know the location of your water shut-off valve, contact the company that supplies your house with water.