HT630ABD - 22 1/2" x 18 1/2" x 6" - 8 US Gallon Capacity. Bottom Drain - RV waste holding tank. The holding tank comes with a 3" Threaded Fitting on the bottom. All seams are solvent welded and have a 1 1/4" mounting flange. This tank typically ships within 2 business days. Handles both black & gray water or a combination of both in the tank Certified to IAPMO/CSA standards Upgrade, increase capacity, or replace a leaky or damaged tank with an industry leading quality ICON tank | Icon Technologies Holding Tank, HT630A-BD, 22.5x18.5x6, 8 Gal