Water pipes are water supply pipes. Modernly renovated water pipes are constructed by buried wall. There are three types of water pipes. The first type is metal pipes, such as hot-dip cast iron pipes, copper pipes and stainless steel pipes. The second category is plastic-plastic pipes, such as plastic-coated steel pipes and aluminum-plastic composite pipes. The third category is plastic tubes. The most used sewage pipe is the PVC pipe and PVC pipe coupling, which is often used in sewage pipes. Let's take a look at the PVC pipe and PVC pipe couplings and fittings used to drain the water.