This paper describes the full-scale laboratory testing (pipe box testing) of a 380-mm-diameter, corrugated, polyethylene toe drain with a knitted geotextile sock, backfilled with a sand envelope material. The test results are compared with previous small-scale and full-scale pipe box tests using pipe with 3-mm and 6-mm perforations, but no geotextile. Use of the geotextile optimized toe drain performance both with respect to flow and with respect to loss of the sand envelope. The long-term flow rate was 260 liters per minute per linear meter of pipe, which was significantly higher (by a factor of 3 to 12) than the earlier tests without geotextile. The total loss of sand envelope was only 165 grams per linear meter of pipe, which was significantly lower (by a factor of 4 to 17) than the earlier tests without geotextile. The test with geotextile was run for 31 days at a constant head of 0.75 m above the pipe invert with no indication of clogging. Based on these results, use of geotextile sock in conjunction with a sand envelope is recommended for future toe drain installations in areas with fine-grained native soils.