The Norwesco 1000 gallon two-compartment septic tank arrives as a single yellow polyethylene vessel with two manhole covers, built to handle the primary settling and secondary clarification stages of an onsite wastewater system in one tank. At 102 inches long, 60 inches wide, and 63 inches tall, it gives you an 8.5 ft x 5 ft excavation footprint with the tank standing 5.25 ft tall, and the two-compartment design separates solids settling from effluent flow so cleaner liquid moves toward the drain field. As a heavy 102-inch LTL item, freight is part of the buying decision: this tank ships from seven Norwesco plants nationwide, and the one closest to your ZIP sets your freight cost.
Will this 1000 gallon two-compartment tank work for your install?
This is a 1000 gallon Norwesco septic tank molded from polyethylene, so it resists the corrosion and tank rot that affect concrete and steel over decades in the ground. The two internal compartments do the work a single-compartment tank can't: the first chamber holds raw waste long enough for solids to settle and scum to rise, and the second chamber gives the effluent a quieter zone to clarify before it leaves the tank. The tank includes two manhole covers for pumping and inspection access. Inlet, outlet, and manhole-cover dimensions are shown on the technical drawing on this page - match your pipe and gasket sizes to those before ordering connections. This tank is sold for septic and wastewater service and carries no published specific-gravity rating for chemical storage, so don't repurpose it for chemical containment. Before you commit to a size, run your bedroom or fixture count through the Tank Sizing Calculator and the Tank Sizing Guide to confirm 1000 gallons matches your daily flow and local minimums. If you're weighing this against a single-chamber design, our guide on single compartment vs two compartment septic tanks walks through why many jurisdictions and modern systems favor the two-compartment layout.
Set, ballast, and approvals
Plan the setting around weight and water. Filled to capacity this tank carries roughly 8,340 pounds of water, which matters both for the bedding you prepare and for resisting flotation. An empty 1000 gallon tank can be lifted by roughly its own water-volume in buoyancy - about 8,340 lb of uplift - if the water table rises around an empty tank, which is exactly why anti-flotation ballast matters before backfill. Polyethylene septic tanks are lighter than concrete going in, but they require correct backfill and, where groundwater is a factor, anti-flotation measures. Verify your local code's burial depth, bedding, and ballast requirements before excavation, and confirm your invert depths against the technical drawing on this page. Approvals are jurisdiction-specific: if you're installing in Canada or a cross-border region, read our breakdown of Norwesco IAPMO and CSA B66 septic tank approvals to see how those listings map against US plumbing codes.
The mistake to avoid
The most common error on a job like this is treating the tank as the whole approval. A 1000 gallon polyethylene two-compartment tank is the right hardware for many onsite systems, but septic tank acceptance rides on your local health department's approved-list and the specific listing that applies in your area. Confirm the model is accepted where you're building before you dig, and confirm whether your authority requires a particular compartment configuration. Don't assume an approval in one state carries to the next. If you're comparing this against other Norwesco doorway and below-grade tanks for a tight access install, the Norwesco doorway tank sizing guide covers the 100 to 1000 gallon range by application.
This Norwesco 1000 gallon septic tank ships LTL freight from the nearest Norwesco plant to your ZIP - production runs from Griffin, GA; Lancaster, OH; Owego, NY; Shawnee, OK; St. Bonifacius, MN; Tooele, UT; and Washougal, WA - so the closest facility keeps your freight down. Get a live freight quote to your ZIP with the Freight Cost Estimator, or call us at 866-418-1777 and we'll size the system and the shipment with you.
