Most homeowners are capable of turning off the water valves under the sink with just a few turns. But if the valves are old, or if they have never been shut off since installation, turning them can cause them to break, and you will have a leak on your hands.

You can prepare for this by having someone stand by the main water turn off and turn off the whole house supply of water if you break off the valve under the sink.

In a development, this main shutoff is usually near the curb and has a lid with a small hole in it. The hole allows the water company representative to open the lid with a small metal rod.

In more rural areas, the main valve may be located in a well house or other exterior assembly. Make sure you locate the main shutoff before you get started on the job.

Clear your workspace and put down some towels and have a pan nearby.

Disconnect the connectors, which are small brass nuts or tin clamps, similar to the clamps that hold the radiator hos to the water pump and radiator in your car.

Look at all of the valves and hoses, and change the ones that look worn or have holes. It should be easy enough to do this if you have the replacement parts handy, and you have Teflon plumber's tape to fix them in place. Sometimes, however, things can go wrong.

If a valve or hose does not come out easily, you may have to use a hack saw to cut it off. Some older valves were welded on, and you should replace these with the threaded kind. Elva enough pipe to re thread, using a retreading tool. If all of this seems too much for you, you may want to hire a plumber.

Older valves and hoses may have several years worth of calcium carbonate deposit built up in them. It is a while chalky substance and when it hardens, it will cause things to stick together. You can usually loosen it with a few twists, but don't pull too hard. If you break a pipe, it will have to be resealed or replaced.

After you have removed the valves, clean them well with steel wool and then sandpaper.

Here is the easy part that can also be somewhat tricky. Wrap layers of plumbers tape to the trended and smooth surfaces where the valves and hoses are going to be replaced. Make sure you thread the tape in the direction in which the valve or hose is going to be turned. The idea is to tighten the tape when screwing on the valve on hose, not to loosen it. Screw on the valve, attach the hose and tighten the clamps without over tightening, just so they are snug.

Now turn the valve on slowly, watching for leaks. If the job has been done right, the threads that fit properly and the tape will make the seal tight and there should be no leaks.

You may have to try again if you do have leaks, but you will get the hang of it. If you didn't over tighten the valves, you should be able to undo the work easily. Redo it to make sure it is done correctly and you will not have to worry about it again for many years.