Polyethylene / Plastic Tanks

When selecting materials for septic system installations, there are trade-offs in each decision, and plastic septic tanks are no exception. The first step to making the appropriate selection for a particular property is to know what polyethylene is good at and when concrete is the better alternative. Rotational molded septic tanks are produced as a whole piece of plastic, meaning there are no seams, joints or connections in the tank body. The seamless construction results in no infiltration or exfiltration, which can occur in multi-section concrete tanks, especially as the joints age and sealing compounds used during installation wear away over time. The seamless construction of a polyethylene tank is a real structural benefit for properties where it is important to prevent infiltration of groundwater into the tank or leakage of effluent from the tank. The corrosion resistance of polyethylene wastewater tanks is an important consideration in locations where the soil or groundwater chemistry would cause the deterioration of concrete over time. High acidity, high sulphate contents or some mineral compositions of the groundwater can attack concrete in a progressive way without affecting polyethylene. When such conditions are found in the soil tests, then a poly tank is not only a convenient alternative, but it is the better long-term option. Lightweight septic tanks made from polyethylene are also significantly easier to transport and position on sites with access limitations. A concrete tank requires heavy lifting equipment to move and set. A poly tank of equivalent capacity can be handled with lighter equipment, which matters considerably on rural Vancouver Island properties where site access is restricted by terrain, narrow tracks, or proximity to sensitive vegetation that heavy machinery would damage.