If the leak stops then you need to replace the cold cartridge.
Fix leaky bathroom sink faucet single handle.
Turn it off and check if the faucet is still leaking.
If the leak doesn t stop after the first valve is turned off it s the other line that s leaking.
The part number of the replacement valves will vary depending on the faucet model number.
Turn the faucet handles to on to release any remaining water.
Determine which side of your faucet is leaking by shutting off the water supply valves one at a time.
Identify your faucet model number.
Figure out which handle is leaking let s start by testing to see which side of the faucet hot or cold is leaking.
To identify your faucet model number please view identifying your faucet model.
Turn off the main water supply.
Once you determine which side is leaking turn off both supply valves.
Alternatively look under your sink for a small valve.
To test to make sure the leak is fixed turn on the water and let it run for a minute.
Continuous leak when faucet is on or off.
This will stop water from gushing out of your faucet when you unscrew it later.
Turn on water make sure the handle is in the off position then turn on the water by turning the knob under the sink counter clockwise.
If your valves are stuck shut off the water main.
Remove disassemble the old faucet.
The issues should be resolved by replacing the valve cartridge.
Press the off switch on your water main box to turn off the water.
How to fix a leaky bathroom sink faucet double handle locate the leak.
Then turn on the faucet to release the pressure and remove any water that may remain inside the water lines and faucet.