The IM-series is a lightweight strong and durable septic/pump tank. Suitable for use as septic tanks, pump/trash tanks, or rainwater (non-potable) storage/harvesting . This watertight tank design is offered with Infiltrator’s line of custom-fit risers and heavy-duty lids. A revolutionary improvement in plastic tank design, offering exceptional strength comparable to concrete tanks. Infiltrator injection molded tanks provide a revolutionary improvement in plastic tank design, offering long-term exceptional strength and watertightness.