By Donna Rider

A greywater system will help you save money on your water and sewer bill and is beneficial for irrigating the landscape. It is not only homeowners that can benefit from greywater; office buildings, apartments, malls, restaurants, and other commercial properties can take advantage of the savings, as well.

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What Is Greywater?

Greywater is considered water that is not clean enough to drink, but not as unclean as water expelled from the toilet. Toilet water is considered blackwater, as are water from the kitchen sink and dishwasher, due to the organic matter, grease, oil, and chemicals.

How Can Greywater Be Used?

Greywater is generally used for flushing toilets, washing clothes and irrigating the landscaping, but it can also be used in any system that uses a lot of water on a daily basis and does not have to provide potability.

How much money you might save depends upon the type of building you are constructing or retrofitting. Here are the likely uses for greywater in various buildings:

  • Most commercial buildings have bathroom sinks and water coolers.
  • Apartment buildings include bathroom sinks and tubs or showers in each unit. A laundry room would both use greywater and collect it. For laundry, water filters would be required if chemicals are used during washing; if only environmentally safe products are used, filters would not be necessary.
  • A mall would have not only bathroom sinks and water coolers but also a food court.

What Are the Benefits of Using a Greywater System?

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The main costs of a greywater system include the plumbing and storage tank large enough to collect the amount of water produced on a daily basis. These installation costs should be offset, however, by savings on water and sewer bills. The more uses you can find for greywater, the faster you will see a return on your investment.

If the greywater will be used to only flush toilets, chemicals in the water would not be an issue, since everything will be flushed into the sewer. Limiting greywater usage to toilets will still have a positive financial impact, saving money on both water and sewer bills. To reap further financial savings, use excess greywater to irrigate the lawn or landscape, but this usage might require the addition of a water treatment or filtering system.

Some states have incentive programs and tax cuts for greywater system installation. Arid southwestern states that are prone to droughts, such as California, would benefit tremendously by greywater systems.

Things to Consider When Installing a Greywater System

If you are going to use greywater to irrigate the lawn or landscape, don’t use softened water. Softened water may contain salt or alkali which can kill some plants. In addition, use soaps and cleaners that are not harmful to the environment. This eliminates the need to filter the water before applying it to the landscape.

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Greywater cannot be stored for later use, unless it is treated. Greywater needs to be used within 24 hours or contaminants begin to decay, and the water will start to smell. This is also the reason you cannot use untreated greywater for a pond or fountain arrangement in the landscape.

Treating greywater is not always a viable financial option, however, because the cost of chemicals can make a greywater system a poor return on investment.

Check with your state environmental health authorities to learn about any regulations for water treatments prior to using greywater indoors. Some states require groundwater and soil tests to be performed before installing the system.


Donna Rider is a Technical Writer with more than 18 years experience researching, developing, managing, and producing on-line documentation and training videos. Ms. Donna Rider gained her expertise in technical writing during her highly successful career in several leadership roles. Specifically, Ms. Donna Rider wrote technical documents to assist the Help Desk Technicians troubleshoot calls from customers at Gateway and Wells Enterprises.