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Marin IJ Articles

Now is the time to harvest rainwater

  • Dave Phelps
  • Water is a byproduct of star formation. It has been established as the essential precursor to life in the universe. The number of planets in the "Goldilocks" zone where water remains in its liquid form in the Milky Way Galaxy is currently estimated at 40 billion planets.

    Luckily, we live on one of those water planets: 71 percent of Earth is covered with liquid water. Only 2.5 percent of the Earth's water is not saltwater, however, and less than 0.3 percent of that is available in the form of streams or lakes and as a component of our atmosphere. The amount of "potable water" on our planet is actually very small.

    Because of our population of more than 7 billion humans and counting, the Earth's freshwater supply is quickly ecoming a scarce commodity. It's value for sustaining life is yet priceless. Thus, the cost of water is and will continue to increase — dramatically. The United States passed its "Peak Water" in 1970. By 2030, the global human need for water is estimated to be 40 percent more than the current supply. Are you ready for that?

    "Whiskey is for drinking; water is for fighting over," said author Mark Twain.

    The human cost of contaminated water is huge, contributing to 80 percent of human illness and killing one in every five children on our planet, about one child death every eight seconds. About 1 billion people are without potable water, and 25,000 humans die every day because of the lack of potable water. The problem is growing.

    Water is also used for power. In North America, each kilowatt-hour of electricity requires 25 gallons of water, contributing to 39 percent of our water use. The World Health Organization has identified the period of 2005 to 2015 as "The International Decade of Action: Water For Life." The end of this decade of action is now only two years away. Have you taken action?

    Agriculture in the U.S. uses 80 percent of our freshwater. In western states that figure exceeds 90 percent. Residential water use is important as well. According to the EPA, roughly 30 percent of the 29 billion gallons used every day by households in the U.S. are used outdoors. For many residential water users, the percentage for outdoor water use is about 60 percent. It is further estimated that at least 20 percent of this water is wasted because of inefficient irrigation practices. That's 5.8 billion gallons of wasted potable water every day.

    In almost every other sunny Mediterranean climate around the globe on subtropical western coasts between 30 and 40 degrees latitude the rain that falls during our short wet season has been historically captured in cisterns that have been designed into built structures. For some reason, most California homes missed this important detail. We are at the point where we need to quickly make up for lost time and an important historical regional design flaw.

    We actually get a large quantity of rainfall during a short period of time. As it turns out, we get more than is economically efficient to store.

    By using efficient roofing materials, gutter straining and "first flush" technology, you could increase your ability of collecting cleaner water to 19,044 gallons per 1,000 square feet. Considering that in Marin, if you are in the third tier of the MMWD's water rates currently at $14.97/unit (748 gallons), for every 1,000 square feet of efficient roof water collection you have in place, you could collect $573 worth of water. That can add up fast.

    Clearly the more people who have their cisterns and rainwater catchment systems in place the better off everyone will be. While this may seem like a feel-good gardening trend at the moment, it could become a very serious issue for millions of people. The proactive gardeners of the land may very well be able to provide the water and food security needed when calamity hits.

    The California Rainwater Catchment Act of 2011, AB 275, allows for landowners and landscape contractors to construct rainwater catchment systems. The act identifies the trend of more and more precipitation in California falling as rain rather than snow and the benefits of private rainwater catchment systems. A "Rain Barrel" system can be installed without a permit.

    Take a moment and consider how you can transform your historic "drainage system" into an "infiltration system" and keep rainfall on your property. Dry creeks, bio-swales and rain gardens might be appropriate. Consider also how you might store some of this valuable resource for summer use or in case of an emergency.

    The time to invest in rainwater harvesting is now.