Contact: (254) 848-4848
Online: Join us on Facebook! Join us on LinkedIn!


According to the Texas Water Resources Institute, Gray Water is defined as the wastewater from clothes washers, showers, bathtubs and sinks that are not used to dispose of hazardous or toxic materials.  It is the “hazardous or toxic materials” that causes some confusion. 

Plainly stated, water from a shower or bath would be considered Gray Water provided no toxic materials (such as human waste or food residue) are present, in which case it would become black water.  The same scenario applies to washing machines, whether or not the water is Gray or Black depends on the types of soil on the clothing. 

Let's look at it a little differently:

Gray Water can only be utilized from sources within a building that will produce no Black Water contaminants.  Once a contaminate is present in the Gray Water supply source, the water becomes Black Water, which requires further treatment prior to reuse in order to avoid possible environmental contamination and public health issues.

Collecting, saving and reusing Gray Water is a great idea and can work very effectively provided the proper precautions are taken to keep it cleanly separated from Black Water. 

To be clear, Black Water consists of:
  • Water containing any form of human waste, including but not limited to blood, urine, hair, vomit, or fecal matter
  • Gray Water stored more than 24-hours
  • Water containing any food particles or residue
  • Water containing paper fibers or plant materials
  • Water containing drugs or pharmaceuticals
  • Water containing insects or living organisms of any kind
  • Water containing solids such as condoms, diapers, sanitary products
  • Water containing sodium and/or gases
  • Water containing any chemicals such as hair colorants, paints, adhesives or emulsified oils

The proper disposal of Black Water is either an onsite sewage facility or sanitary sewer. 

The optimum conditions for Gray Water would be commercial or public restrooms using the Gray Water from sinks to provide water to a small green space such as parking lot planters or flowerbeds.  Gray water can also be an effective water supply for flushing toilets.

Although GW can be very useful, it can be difficult to capture routinely due to the risk of contamination.  For this reason, it is not recommended that individual property owners design and/or implement their own Gray Water recycling system.  Doing so could inadvertently contaminate the environment while the original intent was to exercise environmentally conscious behavior.  It is strongly recommended to consult a professional in the water conservation field before implementing any Gray Water collection systems.

Additional Gray Water Resources:

For detailed information on the Texas Gray Water Code check here.

Texas Water Resources Institute