The Norwesco 500 gallon single-compartment septic tank (SKU N-41320) is an IAPMO-certified polyethylene tank for residential and light-commercial septic systems that need a code-listed wastewater chamber without the weight or cracking risk of concrete. It measures 101 inches long by 51 inches wide by 47 inches tall, so plan your excavation around the 51 x 101-inch footprint. The rotationally molded shell holds the full 500 gallons in one chamber, and the yellow finish is the standard color for this Norwesco septic line. If you are searching for a 500 gallon IAPMO septic tank, this is that tank.
Will it work for your system?
Two questions decide this purchase, and you should settle both before you order. First, compartment count: this is a single-compartment tank, and many newer codes require two compartments for the primary tank, so confirm what your permit calls for. Our guide on single compartment vs two compartment septic tanks shows where each is allowed. Second, certification acceptance: the tank carries IAPMO certification, which is what most plumbing inspectors look for when they list a poly septic tank against the applicable code. Rather than trusting the badge alone, request the IAPMO listing and check it against your permit; the Norwesco IAPMO and CSA B66 septic tank approvals guide covers the certification scope, including Canadian cross-border use. To verify the tank fits your dig, run the dimensions through our Tank Sizing Calculator or review the Tank Sizing Guide, and see the technical drawing on this page for inlet and outlet placement before you set it.
Service rating and what not to store
This tank does not carry a published specific-gravity rating, which is correct for its job: it is built for septic and wastewater service, where effluent runs close to the density of water. It is not a chemical tank, so do not repurpose it for heavier-than-water liquids that would need a higher specific-gravity build. For the install itself, plan your handling around a full-of-water weight near 4,170 pounds. That figure matters most during bedding and backfill, when you should fill the tank with water as you backfill in lifts to balance the soil load and keep the tank from shifting or floating. Follow Norwesco's burial instructions for bedding depth, backfill material, and the water-filling sequence, since a poly septic tank backfilled dry or set in poor bedding can deform.
Freight and ordering
This 500 gallon Norwesco septic tank ships LTL freight, quoted live to your ZIP code from the stocking plant nearest you. We carry it from Griffin, GA; St. Bonifacius, MN; Tooele, UT; and Washougal, WA, and route from whichever plant is closest to keep transit time and cost down. Get an exact number through our Freight Cost Estimator, or call 866-418-1777 and we will quote it and confirm the right tank for your permit. List price is shown above and is before freight.
