Function of Cast Iron

• Cast-iron pipes comprise the drain, waste and vent (DWV) components of a plumbing system. Drain and waste pipes deliver gray water (non-hazardous drain water) and black water (hazardous waste water) to sewer and septic systems. Vent pipes maintain a drain system's balance and help prevent sewer gases from wafting inside a structure through the drain system.
  
  

Installation

• Unlike solvent-welded plastic drain pipes, cast iron typically connects via mechanical fittings. The most common type of cast-iron drain fittings are semi-flexible, sleeve-like rubber couplings that slide over a pipe. A band clamps at both sides of the coupling to secure the fitting to a piece of cast-iron pipe.
  
  

Pros and Cons

• Cast iron is substantially more durable than plastic drain lines. However, cast-iron drain pipe and fittings are expensive and require specialized installation tools such as chop saws or chain cutters.