Water Reuse

Water Reuse

In considering water reuse, it is important to acknowledge that most tap water has had some contact with treated sewage.  Wastewater treatment plants discharge into streams that feed rivers from which other cities pump water for drinking.  By the time New Orleans residents drink the Mississippi, the water has been in and out of more than a dozen cities.  More than 200 communities, including Las Vegas, discharge treated wastewater into the Colorado River which is used as a drinking water source for southern California.  In these natural waterways, most contaminats left in the effluent are diluted, biodegraded, and/or photodegraded.  In addition, the drinking water treatment process removes anything left over.

In a water reuse system, the additional clean up is generally accomplished through technology.  Although the additional technologies increase costs of wastewater treatment, reuse can be cost effective if it is designed efficiently, utilized effectively, and marketed correctly.  In many areas, the cost of potable water is stil less than reclaimed water; however, as the supply of potable water continues to decrease, it will become more cost effective to use reclaimed water.  It is in our best interests to preserve our dwindling water supply by investing in water reuse today.

Some advantages to wastewater reuse include:
  • reduces the demands on potable sources of freshwater,
  • provision of nutrient-rich wastewaters can increase agricultural production in water-poor areas,
  • use of wastewater effluent for irrigation will eliminate the need for nutrient removal at the treatment plant,
  • the quality of the wastewater as an irrigation water supply is usually superior to that of well water,
  • pollution of rivers may be reduced as less wastewater is discharged to the waterways, and
  • provides better quality water for industrial users.

Some disadvantages to wastewater reuse include:

  • reuse may be seasonal in nature (e.g. irrigation, golf course watering),
  • potential for public health problems if treatment system doesn't work properly,
  • not always economically feasible due to the need for a separate distribution system,
  • may result in groundwater contamination, and
  • may result in over application of pesticides if users of reuse water for irrigation are not educated about the nutrients already in the water.

Perhaps the biggest roadblock to wastewater reuse is the public's aversion to using the water.  The phrase "toilet-to-tap" has been used to describe wastewater reuse and in many people's minds, there is an instant "ick" factor when the subject is raised.  Of course, "toilet-to-tap" is no where near the reality of the situation.  Water reuse involves the most state-of-the-art technologies to produce water generally superior to tap water and even bottled water.  Aggressive PR campaigns to educate the community about the actual treatment processes and residual contaminant levels are the best way to combat public aversion.

There are many different ways in which water can be reused. Most reuse activities fall into one of the following six categories:

  • Agricultural Reuse
  • Direct Potable Reuse
  • Environmental/Recreational Reuse
  • Industrial Reuse
  • Indirect Potable Reuse
  • Urban Reuse
Sources:
McKenzie, C. Wastewater REuse Conserves Water and Protects Waterways. On Tap. Winter(2005): 46-51.
Royte, E. A Tall, Cool Drink of ... Sewage? The New York Times. 10 August 2008.