A subsurface irrigation system under construction (Smart Sewage Solutions)
An installed subsurface irrigation system (Whitehead & Associates)
Subsurface irrigation schematic (Ohio Installer)
Subsurface irrigation uses a network of polyethylene pipes located just under the ground's surface to apply disinfected effluent in the root zone of plants, preventing airborne drift and minimising runoff. Note that effluent that has not been disinfected, such as from septic tanks and most wet composting toilets, must be disposed of below the soil (at least 300 millimetres deep).
Subsurface irrigation requires less maintenance than surface irrigation, and there is also less chance of surface saturation and effluent runoff. By reducing the chance of human contact, it also significantly reduces the public health risks.
Common problems with subsurface irrigation are:
- not enough irrigation lines to adequately distribute effluent over the required area
- irrigation lines becoming blocked or damaged
- system not designed or approved for its location
- no service agreement with a qualified service provider for regular maintenance and inspections.