Plumbing is an industry that provides a service to millions of people worldwide. It delivers clean water and removes waste to help us live better and prevent disease. It is an important part of every building and construction plan. Proper plumbing can reduce water bills and prevent rot and mold. In addition, it can improve the aesthetics of your home. Plumbing is an industry that requires skilled labor. It includes installing and maintaining piping systems, as well as making changes to appliances and venting systems. In the United States, plumbing professionals install water heaters, drains, and plumbing fixtures. They can also repair and maintain sewer systems, water softening equipment, and backflow prevention systems. The demand for water, sewage, and drainage has made plumbing an indispensable part of the economy. The proper sizing of a house drain depends on the number of fixtures it serves. The usual minimum size for a house drain is four inches in diameter. Materials used for house drains include cast iron, vitrified clay, plastic, and lead. The top two pipe types for a DWV system are PVC and ABS. Proper sizing will ensure that the water drains correctly. In addition, proper scouring action will help prevent solids from clogging the pipe. PEX pipes are flexible and can weave through walls and other obstacles. PEX pipe is also strong and withstands high water pressure. This material is a great choice for repiping and new construction. Additionally, it is inexpensive compared to other plumbing materials. PEX pipes are also color coded for hot and cold water. They are also easy to cut and come in a variety of sizes and colors.