A sanitary sewer system is the network of underground pipes that collect wastewater from homes, businesses, and institutions and transport it to treatment facilities. This includes water from toilets, sinks, showers, laundry, and other drains. Sanitary sewers are separate from storm sewers, which handle rainwater. Older combined systems carry both but are being phased out due to overflow problems. Wastewater travels through progressively larger pipes to treatment plants where it's cleaned before discharge to waterways. Municipalities are responsible for building, maintaining, and operating sewer systems, funded through sewer rates typically based on water consumption. Sewer capacity determines where development can occur.