Want to Conserve Water? Try Using Grey Water

Written by Anita Alvarez
Updated April 9, 2016
lawn irrigation spicket spraying water on lawn
Reduce water waste by filtering grey water from showers, baths and laundry to use when watering your lawn. (Photo courtesy of Rain Bird)

Take the next step toward a greener home by conserving and reusing household water.

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Homeowners in search of greener options are turning to high-efficiency heating and cooling systems, energy-efficient lighting and grey water systems. The latter can transform not only your water bills, but installing a grey water system in your home boosts your contribution to conserving natural resources.

Much like rainwater harvesting, grey water recycling provides a simple and effective way to conserve water. Before you buy, or talk to your plumber about installing a grey water system, learn exactly how it works to reduce water usage.

How do grey water systems work?

The basic premise of grey water plumbing involves diverting some portion of water consumed in the home away from where most plumbing goes — into the city's main sewage system — and rerouting it for use in the home or outside. In general, grey water units require the installation of a valve near the water application that the homeowner can open and close manually. This provides the option of diverting grey water when desired, and opting for the main sewage system when necessary.

Purchasing a system that lets you choose where to divert the water is particularly useful, especially when outdoor conditions are already moist from rains or snow. At other times, water may be polluted, and diverting chemicals for inside or outside isn't desirable.

Once the user chooses to divert the grey water, the water is routed through a series of special pipes, where it also passes through a filter designed to remove the largest particles in the water. Most systems employ a surge tank, designed to hold water when the system becomes overwhelmed with too much water. A certain amount is diverted to the holding tank until it can move forward for filtration. For example, if you were to empty a full bathtub through the grey water unit, it would overwhelm the system without holding some water in the surge tank.

How can I use harvested grey water?

You can use grey water in a number of places. Most systems generally provide the option to deposit water outdoors, using the filtered water for watering a garden or flower bed. The average grey water is quite safe for plants — most hand and body soaps are as safe for plants and soil as they are for your body. However, grey water with soap is an alkaline, so avoid using it on seedlings or acid-loving plants.

You can also opt for higher levels of filtration, and route the water back into the home for reuse — but not for drinking — in toilets, washing clothes and even cooling systems that run on water.

If you operate on a septic tank, grey water systems offer a a further advantage, since recycling grey water rather than letting it go into the tank limits the amount of water and soap, allowing the septic bacteria to more easily break down waste and reduce the need for periodic pumping. And on a larger scale, for those using sewer systems, running less water into the sewer reduces water treatment costs.  

Grey water system options

Grey water equipment is fast becoming a popular go-to option for homeowners, especially in areas where droughts are common and water is scarce. Reusing water just makes sense when it comes to conserving our nation's natural resources. One of the simplest grey water systems involves running a tube from your washing machine's discharge hose to the outdoors, using the washing machine's grey water to irrigate your lawn or plants without running afoul of local lawn-watering restrictions.  

Simple grey water equipment that doesn't require a pump often lasts longer, and the systems offer a high return on investment. A plumber can also help you with options to take advantage of all the grey water your home produces. Consider that the average American family uses more than 300 gallons of water per day, according to the Environmental Protection Agency. Over the life of the grey water equipment, the potential to save by reusing just half of your household's daily water will add up to significant savings.

With a grey water plumbing system, you can count on saving on monthly water bills, and get peace of mind knowing that you're taking a big step toward using less water.

Do you use a grey water recycling system, or would you like to? Tell us about it in the comments below.

Editor's note: This is an updated version of an article originally published on Sept. 25, 2015.

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