How does a toilet flush? There is no electricity, no apparent mechanical apparatus. Believe it or not, the toilets flushes mainly through siphon power. As the toilet bowl fills with water, it overflows into the exit pipe, and as more and more water escapes, it creates a vacuum that essentially sucks out the remaining water behind it, just like siphoning gas through a hose. Most people don't know it, but you can flush a toilet just by dumping a bucket of water into the bowl. The sudden extra water, whether flowing in from the tank behind or from a bucket, cause the overflow into the exit pipe, making the toilet flush. The other moving parts in the toilet are located inside the water tank, usually behind the seat. A water inlet pipe from the wall feeds into the tank, refilling the tank after each flush. The flushing handle pulls up the flap or stopper that plugs the bottom of the tank, much like in a bathtub, releasing the water into the bowl causing the flush. A toilet is not a super complicated device, so repairs and installation can be handled by a non professional if you know what you are doing. However, toilets involved sewer gases and water, so you want to make sure you do it right. A plumber will probably charge you some amount to remove an old toilet and install a new one (not including the cost of the new toilet). Removing an old toilet involves disconnecting it from the water source, draining it, unbolting it from the floor, and removing the wax seal from underneath.