What system should cast-iron soil pipe and fittings not be utilized in?

Cast-iron soil pipe and fittings are primarily designed for use in drainage and sewage systems. They provide excellent strength, durability, and resistance to corrosion, which makes them ideal for heavy-duty applications where the transportation of waste and sewage is involved.

Using cast-iron soil pipe in water systems is not appropriate because these pipes are not suited for carrying potable water. The materials and construction methods used in cast-iron pipes can affect water quality, potentially leading to contamination or aesthetic issues such as discoloration. Additionally, the weight of cast iron makes it impractical for water supply applications, where lighter and more corrosion-resistant materials, such as PVC or copper, are more commonly used.

Vent systems can accommodate cast-iron pipes as well, because they deal with air and gases rather than liquids. However, the inherent characteristics of cast-iron make it less suitable for applications involving drinking water. Hence, this understanding underscores why cast-iron soil pipes should not be utilized in water systems.