What system types are allowed in Texas, and when is each used?

Table XIII of §285.91 lists the approved disposal methods and the soil classes each is suitable for: standard absorptive drainfield (septic tank version suitable in Class Ib/II/III, needs 2 ft of suitable soil below the excavation), leaching chambers (Ib/II/III, not Class IV), gravelless pipe, unlined and lined evapotranspiration beds, low-pressure dosing, mounds, drip irrigation, and surface (spray) application (30 TAC Chapter 285, §§285.32–285.33 and Table XIII). ET beds may be used where soils are unsuitable for subsurface absorption due to texture, restrictive horizons, or groundwater, require water-saving devices, and are allowed only where annual evaporation exceeds annual rainfall; a liner is required in Class Ia soils or where groundwater enters the excavation; mounds may only be installed where slope is under 10%, and drip irrigation with secondary treatment can work down to 1 ft depth to groundwater (30 TAC Chapter 285). Surface/spray application always requires secondary (aerobic) treatment, vegetative cover, and disinfection, and sits at least 100 ft from a private well and 150 ft from a public water well (30 TAC Chapter 285, Tables X and XIII); rocky disposal areas commonly get soil substitution, ET, pumped effluent, drip, low-pressure dose, or a mound instead (Ector County Health Dept..pdf)).

Reviewed August 2026. Links go to the sources this answer was checked against.