This 1500 gallon septic tank is constructed with rotationally molded polyethylene resin. It's seamless construction makes it durable and resistant to cracks, chips, and ruptures. The poly tank was made with FDA approved resin that complies with FDA standards 21 CFR 177.1520 (1) 3.1 and 3.2 for waste water storage.The 1500 gallon septic tank is IAPMO Certified. It features two 20" gasketed manways, a 4" gasketed pvc tee assembly inlet, and a 4" gasketed pvc tee assembly outlet. Installation requires a 25% internal backfill to equalize the pressure between the outside and the inside of the tank.Norwesco backs their septic tanks with a 3 year manufacturer warranty. Additional riser options are available. These plastic septic tanks are available in sizes ranging from 200 to 3,525 gallons.