Installing a new bathtub can bring a new dimension to your bathroom. Perhaps you want a larger tub or one that's a bit deeper to soak in. Some tubs are installed on concrete floors and they require a bit of special attention to make sure they are set correctly and will last for many years. Acrylic tubs are a popular choice today because they are lightweight and durable, not to mention quite inexpensive.
Apply self-leveling compound with a notched trowel on the concrete where the new acrylic tub will sit. This compound will help hold the tub level if the concrete floor is a little uneven.
Set the new tub in place over the existing plumbing drain and line up with any tub spout plumbing, such as a copper water feed.
Level the tub and use a rubber mallet and a short piece of 2-by-4 to gently tap the tub into its proper place. As you level and tap the tub with the rubber mallet and wood block, the bottom of the tub will slowly sink into the self-leveling compound you spread on the floor.
Screw the tub flange to the wall studs with the cordless drill and drywall screws. Install them about every 6 inches, working your way around the tub flange.
Insert a new threaded drain down into the drain hole and over the male threads already sticking up. The tub's basic plumbing is still being used from the old tub. You are simply installing new hardware to go with the PVC drain piping under and behind the tub.
Install a new overflow assembly. Insert the rod, linkage, and plunger through the tub overflow hole and let it drop down until the overflow cover lines up with the overflow drain hole. Install the screws with a screwdriver and tighten down.
Thread in a new tub spout pipe through the tub spout hole and into the elbow within the wall. Tighten with a pair of pliers. If you have copper pipe, it will already be protruding from the tub spout hole. You don't need to do anything in that case.
Screw on the tub spout with the screwdriver. Test for leaks.