While it is possible to install a bathtub yourself, you should only attempt this if you have some experience working with plumbing. There are a number of steps involved and a variety of problems that can arise, so you should leave the job to a professional if you are a novice. Depending on where you live, your local building codes may require the installation to be inspected by a plumbing inspector. If you do undertake the project yourself, you need to do some advance planning and ensure that you have all of the necessary tools and supplies.
You should start by measuring the dimensions of your existing bathtub. You do not want to purchase a new tub only to find that it will not fit in the space allotted. Once you know the length and width of the tub, you should also plan how you will remove the old tub from the house and get the replacement tub into your bathroom. Depending on the configuration of your bathroom, you may have to temporarily remove your toilet or sink to allow you plenty of room to maneuver. You will also want to purchase a few bathroom tiles in case any of your bathroom tiles are damaged during the process.
Before starting to remove the old bathtub, you should turn off the water supply to the tub or entire bathroom, whichever is easier. Using a special tool, you will need to unscrew the overflow plate so that you can disconnect the drain. The next step is to disconnect the waste and overflow unit located under your tub. You then need to remove the tiles or wall surface above the tub. Loosen the tub by cutting through the caulking with a caulk remover tool. You can also use a liquid caulk remover. After applying the liquid remover, you must let it sit for a couple of hours. Once the caulk is loose, you can use a putty knife to pull the caulk away. After the caulk has been removed, you will need to pry the tub away from the wall. This can be a difficult job, so be sure to have extra help available.
Now that you have removed your old tub, you can start installing your new one. Repair any damaged areas on your walls or floor. Double check the new drain and waste and overflow to ensure that they fit properly. If everything fits, assemble the drain and secure the waste and overflow inside the wall. Slide the new tub into position while being careful not to damage the tub or the waste and overflow unit. Again, you will need some help with this step.
Reconnect the drain line to the bathtub. Check for leaks by running some water. Secure your new tub to the wall studs, and caulk along any seams. Do not forget to caulk around the bottom where the tub meets the floor. If you do not do this, water can pool under the tub and cause extensive structural damage. Finally, install new tiles and faucets as needed.