One of the major tenets of sustainability is to reuse whenever possible. Why not reuse your water? In fact, the concept of water reuse has been around for a long time.

In 17th-century Germany, the man of the house had the privilege of being the first to use the hot bath. After him, the other sons had dibs, followed by the women, then the children, and, last of all, the babies. After so many uses, the water was so dirty you could actually lose someone in it. Hence the expression, “Don’t throw the baby out with the bath water.”

Today, this wastewater is referred to as graywater. Graywater is all the wastewater generated in your home, excluding water going down the toilet. Instead of just using fresh water once, all the soapy water could potentially be used for something else.

Black water is the dirty water from a toilet. Due to its high level of toxins, it’s not used in a graywater system and must be treated in a sewer or septic system.

In the hot and dry regions of the United States, the use of graywater has a long history in watering farmland and crops. Though graywater use has been common in rural areas for decades, recycling graywater is a very controversial subject because of concerns about public health.

Warning: The hair, chemicals, and bacteria in graywater are a minor, but potential, health threat. If someone in your family develops a communicable disease, such as the flu, measles, or chicken pox, stop using your graywater system until the person has recovered. A valve is typically installed to allow you to divert the graywater back to the sewer.

State Regulations

• Arizona: Arizona has perhaps the most open-minded stance on graywater use, though the regulations are still very restrictive. Given the dry climate, the use of graywater makes good sense. Because of this, many people install graywater systems without a permit to avoid dealing with the regulations. Warning: I do not recommend installing a graywater system without a permit — particularly because of the associated health concerns.
  

• California: California’s Graywater Standards are now part of the State Plumbing Code, making it legal to use graywater everywhere in California. Despite the issues surrounding water shortages, the laws only permit graywater use in your yard. Only a handful of individual and prototypical cases using graywater in toilets have been permitted.
  

• Colorado: Graywater use is permitted, but only in below-ground irrigation systems.
  

• Connecticut: A pilot program permits graywater use if approved by the local water district.
  

• New Mexico: In New Mexico, graywater is only permitted for use in irrigating your yard, though several instances of builders using it for toilets have been allowed. For graywater toilet use, the rules vary from county to county within the state, so check with your local building department.
  

• New York: New York offers a green building tax credit that includes provisions for graywater use.
  

• Texas: Texas only permits the use of washing machine water in graywater systems.  ....read more