The Enduraplas 400 Gallon White Horizontal Sump Bottom Leg Tank (SKU THD00400W) is a 400-gallon polyethylene horizontal leg tank built for transport and applicator work where the load needs to ride low and stay put. It measures 74 inches long by 46 inches wide by 42 inches tall, with a 46.0 x 74.0-inch footprint that keeps the center of gravity down on a trailer or skid. The molded-in legs and sump bottom let the tank sit flat and drain toward a low point, so you empty closer to dry rather than leaving product pooled across a flat floor. It is rated to a 1.9 specific gravity, which is the number that decides whether this tank is right for your fluid.
Will it work for your fluid and load?
Capacity is 400 gallons. Filled with water (specific gravity 1.0) the contents weigh about 3,336 pounds. Because the wall is rated to a 1.9 specific gravity, the tank is engineered to carry up to roughly 6,338 pounds of contents at that maximum rating - meaning you can run heavier-than-water fertilizers, brines, and chemical solutions without exceeding what the tank was built to hold. The 1.9 SG rating is the upper density tier for this size and format, so for the fluids below there is no heavier-rated alternative you need to chase. Use that max-rated weight to size your trailer axles, hitch, and tie-downs before you ever fill it. If you are not sure your blend fits inside 400 gallons, run the numbers through our Tank Sizing Calculator and read the Tank Sizing Guide so you order the right size the first time.
Chemical compatibility
This tank is molded from polyethylene with a 1.9 specific-gravity rating. Confirm the resin family - HDLPE versus XLPE - with us before you put any chemical into service, because the resin family changes which fluids the tank will tolerate over time. The 1.9 SG rating is what lets it carry the dense, salty, and acidic loads below, and the sump bottom is a real operational benefit when you run settling coagulants like Ferric Chloride, Aluminum Sulfate, Polyaluminum Chloride, and Ferric or Ferrous Sulfate - it lets you draw off solids and sludge near the low point. Always match your fittings and gaskets to the chemical, not just the tank.
Based on the OEM chemical-resistance chart - which is concentration- and temperature-specific - this tank handles, at the listed concentrations: Acetic Acid (60%) with PP/PVC fittings and EPDM gaskets; Aluminum Sulfate (50%), Calcium Chloride (40%), Ferric Chloride (50%), Ferric Sulfate (60%), Ferrous Sulfate (20%), Magnesium Chloride (30%), Sodium Carbonate (30%), Potassium Carbonate (50%), Potassium Hydroxide (saturated), and Sodium Thiosulfate (40%), all on PVC fittings with EPDM gaskets; Ethylene Glycol (100%) on PVC/EPDM; the agricultural staples Urea Solution (50%) and DEF (32.5%, diesel exhaust fluid) - DEF on 316SS fittings with EPDM; plus Polyaluminum Chloride (PVC, EPDM), Sodium Bisulfate and Sodium Bisulfite (PVC/PP, EPDM), Propylene Glycol and Zinc Orthophosphate (PP/316SS, EPDM), and Ozonated Water (up to 10 PPM) on PVC/EPDM.
The aggressive oxidizers and strong acids need a harder gasket: Hydrochloric Acid (37%), Hydrogen Peroxide (50%), Phosphoric Acid (85%), and Sodium Hypochlorite (under 16.5%) all call for PVC fittings with Viton gaskets; Hydrofluoric Acid (48%) and Hydrofluosilicic Acid (26%) use PP/PVC with Viton; Sulfuric Acid (98%) steps up to CPVC fittings with Viton; and Peracetic Acid (30%) requires 316SS fittings with an Aflas gasket. These high-concentration oxidizers and strong acids are flagged on the OEM chart as conditional, so confirm continuous-storage suitability - not just short-haul transport - with us before filling. The common mistake is reusing one set of EPDM fittings across every product - swap an EPDM seal onto sodium hypochlorite or sulfuric acid and it will fail. Match the fitting and gasket material to your specific chemical, and verify your exact concentration and temperature against the OEM chart and our chemical compatibility reference before filling. Only the chemicals listed above are covered; if your fluid is not on this list, confirm with us first.
Freight and how to order
This tank ships LTL freight from the Enduraplas plant in Neche, ND, quoted live to your ZIP code - get your number from our Freight Cost Estimator before you commit. Outlet and fitting configuration is not listed in our spec data for this tank, so confirm bulkhead and outlet size - along with the chemical-matched fitting and gasket material from the table above - with us before ordering; review the technical drawing on this page for fitting locations and dimensions. For heavier-than-water applicator and leg-tank setups, our guides on applicator and leg tanks for fertilizer and DOT classification for farm-fleet use walk through trailer and roadability questions, and the fertilizer-blend stratification guide covers keeping a dense blend mixed. Call us at 866-418-1777 with your fluid, concentration, and ZIP for help sizing the tank, fittings, and freight together.
