Let's start with the easiest possible project: Installing a new shower head is as simple as it gets. Typically, all you have to do is unscrew the old shower head from the shower arm (the pipe coming out of the wall), clean off the threads on the shower arm and wrap a bit of Teflon tape around it, then screw on the new shower head. It's really that simple (and if you don't believe me, check out the video above from Dummies.com). Do read the installation instructions on the shower head you buy, though. Some are designed not to require Teflon tape and can actually leak if you use it.
When a person has a blockage in their sewage system they often try to fix it themselves by adding an acid or a base such as Drano in an attempt to dissolve or dislodge the problem. These chemicals can get into the plumbers eyes when the sewage is splashed during the repair. The plumbers skin during the repair does come into contact with the sewage water. The owner of the toilet might not report to the plumber they have already tried Drano a highly caustic base .