When considering water usage, what is the relationship between potable, gray, and storm water?

Potable water is clean water from the water authority, which turns gray with any usage. Gray water can be reused in irrigation, where it becomes black water. Storm water comes from rainfall and cannot be used in any manner. Storm water goes into sewers and, eventually, into the clean water processing plant.

Potable water is drinking water only. Gray water is not as clean as potable water but can be used for cleaning, showers, laundry, and irrigation. Black water is water with particulates such as human waste, food, or chemicals. Storm water is both clean rainwater that has been captured for irrigation (rain gardens) and runoff that may carry chemicals from landscaping. All used water goes into sewers.

Potable water is clean water for drinking and all human uses; it turns to gray with washing and cooking uses. Gray water can be re-used for toilets. Toilet water is considered to be black water. Potable, gray, and black water discharge to the sewer. Storm water is surface water runoff that discharges to storm sewers.

Potable water is water that has been chemically cleaned. Water that has not been chemically cleaned is either gray or black depending upon the size and type of particles suspended in the water. Storm water is never considered, since it comes from atmospheric moisture which may also have soil, leaves, debris, and chemicals in it. Storm water cannot be used for any purpose.