Greywater

What is it?

Grey water is all the water coming out of the house that has not had any contact with human waste. Depending on local laws, this can include drains from the bathroom sink and shower, clothes washer, and dishwasher.

In a conventional house, all this water is mixed in with water from the kitchen sink and toilet, and is then pumped off to a wastewater treatment plant, which spends a lot of time and money separating all the waste from the water.

Conventional? How about outdated?

Originally designed to halt the spread of disease through fecal contamination, municipal water system designs are outdated and inefficient. Municipal water system designs manage to actually mix relatively clean shower water with toilet water, and then have to clean out the waste that was originally only in the toilet water.

How does it work

Greywater systems collect water from the sink, shower, bathtub, and laundry drains, and route that water into swales, mulch piles or driplines. The water is then used to irrigate everything from ornamentals to fruit trees. Using greywater not only drastically reduces your water usage, it also converts your water waste into a water surplus, allowing you much greater flexibility in landscape design.

By routing grey water to gardens and other landscaping uses, water can be reused efficiently with the added benefit of using natural processes to clean water, and using the naturally clean water to recharge groundwater supplies.

What are the benefits?

The benefits of using greywater are three-fold. First, you use your water twice as efficiently; once when you wash your hands, and then again when that water goes to your plant. In high-threat environments, using greywater can cut sanitation truck deliveries and haul-outs in half. If you have ever seen a sanitation truck driver in Iraq, you will know that they do not look like the most trust-worthy people.

Second, buildings that use greywater to irrigate the surrounding area enjoy the benefits of a plant-controlled microclimate; shade in the summer and wind-blockage in the winter. Post-disaster areas can use greywater treatment to decrease the load on septic systems, controlling disease outbreaks and sewage overflows.

Third, wherever Exup buildings are located, using greywater prevents that water from having to be transported from the building back to the water-treatment plant, where the water is filtered, chemically treated, and sent right back.

For hundreds of helpful facts and figures regarding green building, energy, and the economy, check out our GREEN FACTS page.