The Norwesco 1500 Gallon Two Compartment Septic Tank is a yellow polyethylene IAPMO-certified tank built for residential and light-commercial septic systems where code calls for a two-compartment design. It measures 135 inches long, 55 inches wide, and 63 inches tall, giving it a 55 x 135 inch footprint that has to be planned into the excavation before delivery. The two-compartment layout separates primary settling from secondary clarification inside a single tank, which is why many plumbing inspectors require it on new installs. This tank ships from a single Norwesco plant in California, so plan freight early if you are installing outside the West Coast.
Will it work for your site
This is a 1500-gallon septic tank, not a chemical or potable storage tank, so size it to your daily flow and local code rather than to liquid weight. Filled with water for testing, the tank holds roughly 12,510 pounds, so the excavation, bedding, and backfill plan have to account for that load once it is set and filled. Confirm your two-compartment requirement and inlet/outlet invert elevations against your county septic permit before you dig. If you are sizing a system from scratch, run the numbers with our Tank Sizing Calculator and read the Tank Sizing Guide, then compare layouts in our guide on single compartment vs two compartment septic tanks.
IAPMO certification and approvals
This Norwesco 1500 septic tank carries IAPMO certification, which is the listing many jurisdictions reference for plastic septic tanks. Approval still varies by state and county, so verify acceptance with your local health department before purchase. For how the IAPMO listing and CSA B66 interact across plumbing codes, see our breakdown of Norwesco IAPMO and CSA B66 septic tank approvals. The technical drawing on this page shows the dimensions, compartment layout, and port locations to check against your system plan.
The mistake to avoid
The most common error with a tank this size is treating it as self-supporting in the ground. A 1500-gallon poly septic tank depends on correct bedding, uniform backfill, and proper burial per the manufacturer instructions and the technical drawing, especially given the 12,510-pound filled load. Skipping the prescribed install steps to save time on the excavation is how tanks shift, deform, or float in high water tables. Follow the install detail, not a shortcut.
This tank ships LTL freight from the Hanford, California plant, quoted live to your ZIP code. Get a delivery number with our Freight Cost Estimator, or call 866-418-1777 and we will walk you through fit, approvals, and scheduling. Listed price is before freight; LTL is quoted separately to your delivery address.
