Sewage, also known as wastewater, is a type of liquid waste. Sewage can be domestic sewage, industrial sewage or storm sewage. Sewage makes up part of the water cycle and it provides a valuable source of nutrients for our soils which need it in order to maintain healthy levels of fertility. Sewer systems play an important role in society because they carry liquid waste from homes, businesses and industries to treatment facilities where it is processed before being returned to the environment. Sewer line plumbers can help in instances where you have a cracked sewer line spewing sewage.