With the United States Drought Monitor’s most recent report that over half the country is facing abnormally dry or drought conditions, now is a more important time than ever to think about greywater harvesting. According to the U.S. Drought Monitor, approximately 52% of the United States, including the normally rainy northwestern state of Washington, is in the midst of drought and is facing the reality of water shortages. Though much of the country is facing short-term drought or dry conditions, meaning six months or less, the majority of the west and northwest is in long-term drought conditions, meaning six months or more. Regardless of whether the U.S. is facing long or short-term drought, integrating water harvesting systems into the infrastructure is an important sustainability measure for dry conditions now, and for overall water sustainability for the future.
Greywater, also known as “graywater” or “grey water,” is different from other on-site water sources such as rainwater or condensate as it has already been gently used. Greywater is the water from sinks and showers, and is highly reliable for water harvesting as it provides a constant source of recyclable water, especially in residential buildings where shower and bath water are readily available. Harvesting greywater is an excellent way to get other uses out of water that would normally end up as sewage.
Once treated, sanitized, and pressurized, greywater is then classified as “on-site treated non-potable water” and can safely be used for toilet flushing and other non-potable uses. The amount of sink and shower usage in a building usually coincides with toilet flushing, so there is supply every day to meet demand. In most cases, greywater harvesting can easily supply 100% of the building’s toilet flushing needs and still have water remaining for irrigation or cooling tower make-up. That daily availability also greatly reduces the cost of water storage as compared to a rainwater harvesting system. A typical residential building can easily save one to three million gallons of municipal water per year with greywater harvesting.
Although states facing long-term drought such as California have already begun greywater harvesting, other western states facing long-term drought and even those facing short-term drought could benefit from greywater harvesting. Because precipitation cannot be controlled and is often an unreliable source of recyclable water, greywater harvesting provides a constant source of reusable water, reducing pressure on the municipal water supply, which is especially important in drought conditions.
Wahaso – Water Harvesting Solutions has extensive experience in developing and managing greywater systems for commercial properties. Our processes remove all suspended solids and thoroughly sanitize the water so it is crystal clear and safe for reuse to flush toilets, irrigate landscaping or make up water to evaporative cooling towers. Wahaso’s process meets the stringent NSF-350 standard for commercial greywater reuse. For more information about Wahaso’s greywater harvesting systems, click here or contact us today!
About the Writer: Emily Avellana is a senior majoring in marketing at Elmhurst College and a Marketing Assistant at Wahaso.