Both cast Iron pipes and Plastic pipes are suitable for kitchen. The cast iron pipes are easy in manufacturing, laying and jointing so; these pipes are extensively used for drainage. They are fairly reliable, best suited for pressure mains. Because of thickness they can bear up external loads better than steel pipes.

Heavy duty plastic pipes are suitable for kitchen. These pipes are light in weight, tough, resistant to chemical attack and available in large lengths. Due to lesser number of joints there are less chances of leakage. These are immune to corrosion. Smooth internal surface of the plastic pipes offers less friction ad saves the energy in the conveyance of water.

Be sure, while laying the top surface of the plastic pipes is covered with cement concrete block.

You can use plastic pipes in the kitchen for drainage but the pipes should be heavy duty plastic pipes with proper jointing and be laid carefully covering the top surface with cement concrete block.