Okay, thought I'd tackle a new one.
Every now and then when someone is taking a shower there is way too much water still coming out of the spout. Waste of water.
Most showers that are also in tubs have 3 handles. Hot and Cold water and a center handle called a Diverter.
The Diverter is exactly that, a device that diverts water one way or the other. Almost all of them have a screw assembly in the middle of them that force the valve open, or closed.
Here is what a common diverter valve looks like.
On the right do you see the white plastic washer? That is what is causing your water to flow down the spout so much while taking a shower.
It is about 15 cents. The whole valve is under 12 bucks.
The trick is to get to that piece.
The first step is to take off the handle. Really old handles will be almost welded on and could break off the tip. If this happens the whole valve needs to be replaced.
Once the handle is off you should see a white plastic thread piece that is covering the shaft of that valve. There is often a silver piece called an escutcheon threaded onto that piece.
It will look like some variation of this.
Remove that piece and now you see the exposed diverter valve. Back on the valve picture from left going right you see a threaded nut screwing into the valve housing. This is called a Packing nut. If you ever see water coming out of the middle of one of these valves all you have to do is tighten that packing nut and it should shut it off.
The valve assembly where that packing nut screws into has a place for a wrench or a socket. You see this area right before a second set of threads. If you cannot get a wrench on that area you will need a plumbing socket. They look like this.
That whole set is about 10 bucks.
Place that socket on the valve and remove the valve from the wall. Really not hard at all.
Once the valve is removed put the handle back on the shaft of the valve and turn it. It will begin to extend out the back of the valve. Take it all the way out. Slide the new plastic washer on and put the shaft back in all the way until it is flush like the picture above shows.
Now use the socket and put the valve back in and then re-assemble your handle.
The whole process if you have the parts should only take you about a half hour as an amateur. If you have to buy the tools and the valve both you still are going to pay less than 30 bucks.
A plumber will charge you at least 75 bucks to do this and you can't keep his tools.
If you have the tools or don't need them and only need to replace that washer. It'll cost you a quarter and the gas money for your trip to the store.