Wastewater is used water. It includes substances such as human waste,
food scraps, oils, soaps and chemicals. In homes, this includes water
from sinks, showers, bathtubs, toilets, washing machines and
dishwashers. Businesses and industries also contribute their share of
used water that must be cleaned. Wastewater also includes storm runoff. Although some people assume
that the rain that runs down the street during a storm is fairly clean,
it isn't. Harmful substances that wash off roads, parking lots, and rooftops can harm our rivers and lakes.