Soil profile analysis vs percolation test — which Texas requires, when each is allowed, how each is performed under 30 TAC 285.

Texas requires a soil profile analysis: §285.30(b) prescribes two borings or backhoe pits excavated to two feet below the adopted excavation of the disposal area or to a restrictive horizon (whichever is less), followed by texture classification, gravel analysis, restrictive-horizon determination and groundwater observation — the rule text contains no percolation-test procedure (30 TAC §285.30), and the TCEQ rules compilation likewise states no percolation-test requirement or procedure, listing only the profile/texture-based site evaluation (TCEQ RG-472, OSSF Rules Compilation). The shift dates to the December 1996 rule revisions, which "eliminate the percolation test as the sole factor for determining whether an OSSF is feasible for a particular site" and "establish a site evaluation process based on soils analysis" (Texas Water Resources Institute, Insights). Sizing therefore keys off soil class rather than a perc rate; a permitting authority may require additional borings or pits in areas of high soil variability, and disputes over groundwater are resolved with the county NRCS soil survey or a certified professional soil scientist (30 TAC §285.30).

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