how do i stop a leaky one handle faucet?

You'll have to get the right tool to pull the "valve stem". Figure out which brand of faucet you have, go to a hardware store and get the kit to fix it. Then turn off the water both hot and cold, usually you have to pop a cover off to unscrew the handle, then use the valve stem pulling tool to pull the stem and replace the o-rings or the whole stem, depending on your faucet. $10-$15 for you to fix, $40 to call a plumber. It's an easy fix, but follow the directions on the replacement parts.

Depending on where the leak is (i.e dripping faucet, or water coming out of the lever joint) you have a couple of different options. For a simple drip - the easiest way to fix your faucet is to replace the o-ring or washer. Generally speaking, you can find a replacement O ring at your local hardware store - all you need to know is the manufacturer of the faucet. If the leak you are referring to is at the base of the faucet (in between the lever and the base), the problem is likely a rubber washer within the valve stem. If this is the case - your best bet is to replace most (if not all) of the washers b/c you never know which one has gone bad. If all else fails - and you get tired of messing with it - your final option is to just replace the faucet - which is honestly about the same amount of work as replacing the O ring.

Hope this helps.

There are several types of single handle faucets. Try this link to help identify the type of faucet. It should give you some help.

http://www.hometownstores.com/howtodir/valves/valv...

Hope it helps.

Faucets usually leak because of old gaskets or o-rings and corroded valve seats.

replace the rubber "O" ring on the stem

buy a replacement cartridge for it.

you'll do better by replacing it.