Which material is acceptable for the line from the building to the treatment tank?

The correct option is the one that includes cast iron, SDR 26 plastic pipe, and Schedule 40 plastic pipe. These materials are deemed acceptable for the line from the building to the treatment tank because they possess the necessary durability, resistance to corrosion, and structural integrity required for wastewater conveyance.

Cast iron is a traditional material known for its strength and long life when used in sewer applications. SDR 26 plastic pipe and Schedule 40 plastic pipe are also widely accepted due to their lightweight nature, ease of installation, and resistance to various chemicals that may be present in wastewater systems. These attributes make them suitable choices for connecting buildings to treatment facilities.

In contrast, the other materials listed do not meet the established standards for such applications. PVC only, while commonly used in standard plumbing, may not provide adequate strength or resilience for specific wastewater applications. Schedule 20 plastic pipe is typically not rated for the same pressure and structural requirements as Schedule 40 or SDR 26, which limits its applicability in this context. Lastly, galvanized steel pipe is prone to corrosion when exposed to the elements and could lead to leaks over time, making it a less favorable choice for a wastewater line.