300 Gallon Above Ground Low Profile Septic Job Shack Holding Tank in White

The 300 Gallon Above Ground Low Profile Septic Job Shack Holding Tank is a Norwesco polyethylene utility tank built for above-ground holding service where headroom is tight - construction job-shack waste, septic holding, and similar 300-gallon collection duty. It carries a 1.5 specific gravity rating, the higher-density classification you want when contents run heavier than water, and it ships with a threaded lid as its one documented penetration. Full water weight is 2,502 lb, and at its maximum rated 1.5 SG contents the tank loads to 3,753 lb - the number that drives your pad and support design.

Will it work for your application

This is a 300-gallon white polyethylene holding tank rated to 1.5 specific gravity, so it handles standard septic and holding-tank liquids that run heavier than water without exceeding its density class. The one fitting on the documented spec is a threaded lid for sealed access - any inlet, outlet, or vent you need will be field-cut and fitted by your installer, so plan for bulkhead fittings and gaskets rated to your contents, and confirm the lid seal is seated before service. Check the technical drawing on this page for the low-profile footprint so you know it clears your overhead and sets level on its base, and verify every penetration against that drawing before you plumb it. Use the Tank Sizing Calculator and Tank Sizing Guide to confirm 300 gallons matches your holding interval and pump-out schedule.

Setting it on a pad

An above-ground tank that loads to 3,753 lb full needs a flat, fully supporting base. Polyethylene flexes and settles, so the support has to carry the entire footprint, not just the perimeter. Our guide on concrete pad sizing for above-ground polyethylene tanks walks through the ACI 360R-10 framework for sizing that slab. If this tank serves a permitted septic installation, the Norwesco IAPMO and CSA B66 septic tank approvals guide covers where Norwesco septic approvals apply across US plumbing codes and the Canadian cross-border scope - read it to confirm whether the approval you need applies in your jurisdiction.

The mistake to avoid

The common error on a 1.5 SG tank is treating the full-water number as the load it will see. Water fills this tank to 2,502 lb, but at the rated 1.5 specific gravity the contents reach 3,753 lb - size your pad, anchoring, and any structural support to the 3,753 lb figure, not the water weight. That 1.5 rating is a paid-for margin, not a derate: you can run contents up to the full 3,753 lb without stepping to a heavier-spec tank. If you plan to track throughput or reconcile pump-out volumes, our tank gauge calibration guide adapts UST accountability discipline to above-ground poly tanks.

This tank ships LTL freight from the nearest Norwesco plant - Fairfield, TX or Lancaster, OH - quoted live to your ZIP. Two origins usually means a shorter haul and a lower rate, and the Freight Cost Estimator picks the plant that quotes best to your delivery point. Get your exact rate there, or call us at 866-418-1777 for help with sizing, fittings, or a freight quote to your jobsite.