Approaching the challenge of how to replace a toilet involves selecting a new fixture, removing the old fixture, inspecting for problems, and actually installing the new toilet.
While a professional plumber can typically complete this task in under an hour, a homeowner might plan on a half day or more.
To find a compatible replacement toilet, first find the “rough in” dimensions of your existing fixture. To do this, measure the approximate distance from the two floor bolts to the wall behind the toilet. Typically, this is about 12 inches, though other sizes of fixture exist. At your retailer, request a similar toilet. Also, if the toilet you are replacing is very old, it might be non-standard, so take a photo and discuss this with your retailer.
The next and critical step before actually removing and replacing a toilet is to turn off the water supply to the fixture. In most installations, this is simply a matter of turning off the supply valve located to the left of the toilet. If you don’t find such a valve, you will need to turn off the water supply to either your home or the bathroom; these are usually located in the basement or crawlspace.
With the water off, flush the toilet to remove as much water from the tank and bowl as possible. At this point it is a good idea to wear latex gloves. Stuff some old newspapers into the bowl to soak up excess water and have some old towels ready as invariably things can get a bit wet and messy. Then, unscrew the nuts on the mounting bolts and lift out the toilet. Careful, they are heavy! After removing the toilet, remove the wax gasket in the floor flange.
Inspect the installation area for problems. Typical problems include rotted out flooring and damaged flanges, or rusty bolts. Sometimes you can remove and replace the mounting bolts easily by sliding them out of the flange. If you run into floor or flange issues, get advice from a professional on how to replace a toilet or contact a professional plumber for direct assistance.
Finally, unpack and assemble the new toilet. Read the instructions carefully! Usually “some assembly is required”. Then, put a new wax gasket into the flange in the floor. Sometimes this gasket is supplied with a toilet, but it frequently is not. So, make sure to have a good new one on hand. Poor gaskets create leaks! Place the gasket carefully on center in the floor flange. Then, place the toilet over the flange and mounting bolts, tightening the bolts. Connect the water supply, turn it on *slowly* and inspect for leaks. Finally, flush the toilet – congratulations and nice work!