How do I repair a leaking valve under the bathroom sink?

Packing is a soft material in the valve around the stem. the valve has a stem. the stem is what turns the water on and off. around the stem is a packing nut. The packing around the stem can be tightened by snugging the nut, but not too much as this will make the stem too tight and the valve will be hard to turn. JUST tighten the nut.

that's spoke of as the water furnish valve and you're fortunate and be waiting to tighten the nut that fastens the tube going out of the valve yet whilst that would not paintings you will could see if the water is coming from the valve or the pipes to or from. If unclear turn off the water to the domicile and take the valve to a solid ironmongery shop and that they could sell you the areas to repair it.

Leaky Bathroom Sink

If the leak is right under the handle, take a wrench and snug up the nut. This indicates the packing nut is leaking. No big deal.

These things can be a pain... in order to shut off the water suppy to this valve you probably have to go right back to the valve that connects you to the water main - usually outside your house close to the water meter. Then you can turn on the tap for a second to de-pressurize the pipes and repair/replace the leaking valve.

If it is a relatively new valve you can probably get a rebuild kit for it and avoid having to solder anything (you just take a wrench to the top of the valve and remove the valve cylinder).

If its an older valve you may need to actually replace the entire valve, in which case you need a torch and solder to remove the old valve and put a new one in. If this is the case then you will be better off just calling a plumber... making a good seal is difficult if you are not used to doing this, and repressurizing the system after a bad repair can be a much worse experience than the drip that you are dealing with now.