There are other skills plumbers need aside from being able to work with water. One of the most common things that a faucet replace on is fixing water lines.
The wax ring is used to seal the drain outlet on the bottom of the toilet to the drain opening in the floor. When a toilet is installed, the ring is placed onto the drain... the toilet is dropped onto the ring... and the toilet bolts (also known as closet bolts) are tightened enough to lock the toilet in place. If that wax gasket ring starts to fail or isn't seated properly? Sewer gasses can sneak out from under your toilet causing your bathroom to have that suspicious smell. It can also cause water line repair to escape, sometimes invisibly, with each flush potentially damaging the floor hidden under the toilet.
After you have the stems out you should be able to find the washer on the "inside" end. If it is nicked, torn or brittle it is likely the cause of your drip. Even if it looks brand new, go ahead and replace it. You've already come this far. You can get replacement washers at almost any hardware store. Sometimes you may want to replace the whole stem, especially if the handle end is stripped out. It's best to just take the stem with you to the store and see if you can match it up. Most Do It Yourself stores have replacement stems for many popular brands. If your valve has a center diverter valve to switch the waterfrom the tub spout to the shower head the same process applies. Many times it is easier to replace the diverter stem than to repair it. This really depends on the design of the stem.
Blisters in asphalt or felt roofs only need to be treated if they contain water or have caused the roof covering to leak. Press the blister to check if moisture is expelled. If so, it must be sealed with a patch.
Keep an eye on any leaks in and around the house. Inspect taps, pipes and your roof regularly. Watch for leaks and if you find them, get it water line repair as soon as possible.
To avoid this, make sure your toilets screws are always tight and repair any leaks right away. A new wax ring should also be installed any time the toilet is removed such as if you happen to be replacing an old toilet with a newer model that you liked such as a more modern KOHLER brand. Replacing your toilets wax ring is pretty simple to do and can pretty much be done in less than an hour by the average person.
Plumbers can help keep small problems from becoming large problems. Do your homework before choosing a plumber and you can help to ensure that the job is done correctly and for a good competitive price.