Many of you probably think I'm nuts by harvesting rain water in Seattle. After all, water is plentiful here, right? While is it true that we get a lot of rainfall, up to 60 inches per year in some places, the summer months can be very dry. Climate change has made our winters here warmer and there is less snow in the mountains to fill our reserviors during the summer. Watershed collection for our growing urban population can offset critically needed water from rivers during the fall salmon spawning season. Recent summers have been dry enough for the local government to call for voluntary and sometimes mandatory water use restrictions.
While it doesn't come close to making up for our gas-guzzling, high-consuming lifestyles, rain havesting does have a positive impact on our environment. Domestic potable water collection requires effort, energy, and chemicals for purification and transport. Toilets use 20 to 25% of water consumed in a residential house. Why are we flushing drinkable water down the toilet? In some other countries of the world, rainwater harvesting on a residential level is a mandatory part of building codes.
Your house is an "impermeable surface". Rain would otherwise hit the ground where your house is and soak into the underground water table or enter a natural stream. Instead, rainfall from the roofs of homes in some older cities is tied into the sewer system. During periods of heavy rain, this storm surge from houses, parking lots, and streets into the sewer system can max out treatment capacity, causing raw sewage to flow out untreated into waterways. Harvesting some of this storm surge can reduce peak demands on our water treatment facilities.
Besides the more important environmental issues, most of us in urban areas pay for domestic potable water. I have calculated that each flush of the rainwater toilet (1.6 gallons) saves me just over 1 cent. Costing less than $100 to install, this system will pay for itself over the years.
Also, I have the satisfaction of a small level of self-sufficiency from an urban lifestyle otherwise dependant on society for survival. |