Drainage pipes are a very important factor in plumbing. Drainage pipes should be selected according to the utility of the house. The positions for the drainage holes should be predetermined. These holes should be situated at a proper distance from the well. Usually the drainage pipes used in houses are of 4 inches. Drainage from all the different pipes in the house should terminate at this pipe. There are some factors to be considered when installing it. A ten feet pipe should have an inclination of one inch. As the length of the pipe increases, the slope of the pipe should also increase. A manhole should be situated in the pathway of the way, mandatorily. If situations arise were the pipes experience drainage blocks, these manholes will prove very helpful.