Dig a hole under the location of the shower slightly wider than the plastic container.
Poke holes on all sides of the plastic container with an awl.
Wrap the plastic container with landscape cloth.
Set the container into the bottom of the hole, pulling the landscape cloth tight around the edges of the container. Fill in any space between the landscape cloth and the surrounding hole with soil.
Set the drain on top of the container to act as the shower drain. Water from the shower will collect in the plastic container, which slowly releases it into the surrounding soil.
Cover the ground around the drain with smooth gravel for drainage and to provide a standing surface that will not get muddy.
Shut off the water supply to the house.
Dig a 24-inch deep hole with a post hole digger slightly behind and between the plumbing rough-ins installed by your plumber.
Insert a 7-foot post into the hole and back fill the hole with soil. This post supports the pipe for the shower.
Unscrew the caps sealing off the hot and cold water pipe rough-ins standing up from the ground where your plumber installed them.
Connect two lengths of straight cast iron pipe long enough to reach from the rough-ins to the height you want to install the shower valves. Cast iron pipe has threads and only needs to be screwed together to make a tight-fitting connection.
Screw the ends of the straight cast iron pipes into the bottom of the shower valve kit. Install the hot water line into the left-hand side of the kit and the cold water into the right side of the kit.
Screw a length of straight cast iron pipe into the top of the valve kit to extend to the height where you want the shower head.
Attach the base of the shower head into the end of the cast iron pipe.
Secure the length of pipe from the valves to the shower head by tying a rope around the post and pipes.
Turn the water supply back on to the house and test the shower.