Our homes contain a network of waterlines coming into the house and supplying water to all of our sinks, showers, bathtubs, washing machines, dishwashers, toilets, etc. Where water comes in it must also be removed by a network of drains and drain lines. Most people assume that when they turn on the water or flush a toilet the water goes down the drain and goes away, which is true but there is a bit more involved. Each drain has its own drain line and each of the drain lines ties to a larger main line that carries the waste water from the house. Drain lines throughout the home work on the simple principles of gravity. All drain pipes are angled downward slightly, approximately ¼” per foot, to keep the waste water moving toward the main line and then out of the home to a sewer or septic field.