Recycling Water
Fish tank water is high in nitrogen and phosphorous making it a great fertilizer should you decide to recycle it by watering your plants.
While the use of gray-water to irrigate may seem to be an ideal way to reuse water that has been used for washing dishes, laundering clothes, or bathing extreme care should be taken to ensure the health and welfare of your family and/or neighbors is not jeopardized. Gray-water contains grease, food particles, hair, and any number of other impurities which should be considered.
Toilet flushing may be the best way to reuse gray-water however DO NOT put the gray-water into the toilet tank. Gray-water in the tank may not only cause the flushing mechanism to malfunction, but could be back-siphoned into the fresh water supply.
High bacteria counts will cause objectionable odors if you attempt to store the gray-water; use it the day it is collected.
Precautions should be observed as gray-water may contain sodium, bleach, or borax all of which can damage plants. Liquid fabric softeners and detergents with softeners should not be used when washing your clothing; dryer fabric softener sheet should be used instead.