What Size Is a Standard Shower Outlet?

Water Delivery

• Water is typically delivered to a home from a utility main or a pumped well-head. That supply enters a common plumbing system; “common” means that all taps and appliances are served by that one source. In larger installations, for instance factories and RV parks, there may be separate supplies for drinkable and non-drinkable water; the drinkable kind is properly referred to as potable. The difference is that potable water has been through more treatment processes, and so is more costly. Some municipalities also run separate mains to landscaping sprinkler systems.

Plumbing Systems

• The main runs of water pipe around the home, both hot and cold, have for many decades typically been made from 3/4-inch copper tubing. Homes built since the turn of the century, and larger buildings, may use a 1-inch pipe. Branches off that main circuit to feed separate taps and appliances are typically made from 1/2-inch pipe. Heavy water-use appliances such as hot tubs or remote bathrooms where the taps, shower and toilet are all rated as a single appliance are usually served by 3/4-inch branches. In the latter case, the 3/4-inch pipes are adapted down to 1/2-inch pipes that serve the individual fixtures.

Drainage Systems

• All plumbing fixtures should have a sanitary water trap, commonly called a “P-trap,” immediately beneath their drain; this trap stops foul odors from the sewage system entering the building through the drain hole. These traps are typically installed within the supports of sinks and are almost always an integral part of a toilet’s design, but are beneath the floor under most showers. To make fitting showers to preinstalled drainage systems easy and convenient, these drain connections are also standardized; the norm is 1 1/2 inches.

Standard Sizes for Showers

• The standard plumbing system outlet that supplies water to a shower is 1/2-inch.

  For regular domestic installations, the standard size for a P-trap fixture below a shower is 1 1/2-inch.