How to fix a leaking Moen bathroom faucet? This will also take care of any water that may be leaking from around the handle as well, not just the faucet head. If you haven’t fixed one before, you may think that it means you’ll need a whole new Moen faucet. What’s happening in the cartridge inside the handle is worn out and can no longer hold back the water pressure. Thus causing the leak. The first thing you’ll want to do is figure out which cartridge is bad, by turning off the water supply one side at a time. It started with the cold side and after closing that valve notice the faucet was still leaking. So the problem is coming from the hot side. Shut off the water flow by rotating the knob until it won’t turn anymore. As you can see the dripping stopped and now we can take apart the handle without having to worry about getting wet.
Depending on the brand and model of your faucet, you may have to use an Allen key in order to disassemble the handle. But for this one, it’s just a matter of unscrewing a few pieces. So now that the handle is off, we’ll need to remove the nut which is holding the cartridge in place. Grab some channel locks and loosen the nut until you can take it off by hand. There is a tool that makes this a lot easier to get out. But if you don’t have it then use a small flat-head screwdriver to loosen the cartridge. Before grabbing those channel locks again.
Soak up some of the water that’s inside the handle when you’re trying to install the cartridge. This will happen so try to get as much water out as possible before installing the new cartridge. It’ll save you some cleanup hand tighten the nut and then use the channel locks to Snug it down after tightening the nut. If you notice the faucet itself is loose don’t worry about it because that will be fixed last. Now you’re ready to install the handle pieces turn the water on and let it run for at least one minute. While that’s running go ahead and inspect the areas around the faucet and water lines for any leaks. Lastly to fix the loose faucet all you need to do is tighten the locknut by hand.