Outdoor showers can serve as practical, enjoyable and attractive additions to a landscape or building exterior. Although piping water to the outdoor shower may be given top priority, figuring out where the waste water will go and how it will be directed can be equally as important. There are multiple drainage possibilities, but a handful of factors or limitations must be accounted for.
Several factors should influence the drainage system design used for an outdoor shower. Municipalities often have ordinances that address outdoor shower construction and where water can drain to. Consult all utility providers prior to digging to avoid coming into contact with any buried utilities. Soil type, predicted usage or volume of waste water produced, proximity to existing structures, and whether or not there is a perimeter drainpipe or French drain already present -- all are important considerations. Poor drainage can flood buildings, cause damage to landscapes or structures, and contaminate ground or surface water.
Under certain conditions, it may be suitable to simply let waste water fall onto the ground. This approach is most suitable where soil has a sand content and where water can percolate quickly and will not collect or build up. This type of surface runoff is not legal in some areas or under some circumstances.
Dry wells are common drainage options where soil is not sandy enough to withstand direct runoff. A dry well is essentially a layer of gravel through which the waste water must percolate and filter. Dry well specifications may be governed by local ordinances, but a recommended size is an area that extends about 16 inches beyond the shower perimeter on all sides to a depth of about 4 feet.
A shower pan is a shower drainage option that involves catching and directing shower waste water. Pans are often installed below the floor or are incorporated into the shower floor and can be plastic, fiberglass, rubber-lined or metal. The pan is connected to a drain that is either hooked up to the system that manages the household waste water, or directed with hosing to irrigate trees, shrubs, ornamentals or select food crops.
In areas near lakes, streams or other bodies of water, it is commonly required or recommended that waste water directly enter a septic or municipal sewer line rather than be allowed to drain freely. In this case, a shower pan or drainage system connected directly to the floor may be most suitable.