Standard showers include the pre-fabbed showers that come with a tub or shower base, plus the surrounds that adhere to your shower walls to protect them from water. These showers range in size, but many stocked units are 79 inches -- or about 6.5 feet -- tall, so it suits most average sized individuals. You'll also find units that are 70 and 72 inches tall. The advantage of a taller shower is more protection for your surrounding walls.
If you're building a custom shower you can set the height at any distance from the floor. The choice is really up to you, but if you want a more functional shower, consider setting the head a little taller than the tallest individual using the shower. This way, the user can run water over his head to rinse. Consider the height of the shower head itself, not the shower pipe -- which is set a few inches above the shower head -- because the pipe tilts downward.
Shower Panels and Waterfall Units
A shower panel -- or a waterfall shower head -- often installs slightly higher than a regular shower due to the position of the shower head and its function. The waterfall shower rains down over the user, so it must be set several inches over her head. Some units don't send a stream of water on a diagonal, but rather straight down. In this case the person must fit underneath the shower. If your panel has a regular shower head, you can install it as you would a normal shower.
The height of the shower head also affects the height of your shower walls. Since shower heads tilt from side to side, you don't want a shower head positioned above the shower walls. The shower head could spray water directly onto the walls if it's inadvertently moved to one side. Extending the walls up and above the shower head by 1/2 foot or more is an ideal solution. Typical shower walls rise above the shower pipe by 6 or more inches in most homes.