New Publication Details 20 Years of Rainwater Harvesting
One Tucson household has released a report describing their rainwater harvesting efforts over the past two decades to show that rainwater harvesting is a viable option for conserving water in the arid southwest. Biologists Charles J. Cole and Carol R. Townsend installed a rainwater harvesting system in their home in the Tucson Mountains, allowing them to gather enough water to fully sustain nearly all their household water needs, including providing for a vegetable garden and swimming pool.
From 2007 to 2024, Cole and Townsend recorded an average of 10.9 inches of rain annually. They observed no long-term decline in precipitation, though rainfall extremes have become more pronounced. Their rainwater collection system features roof capture, filtration, a 26,000-gallon cistern, and advanced treatment with UV, activated carbon, and reverse osmosis. They gained inspiration for this system based on their experience with similar systems in Guyana. They documented that a half inch of rain on their property supplied them with about 1,300 gallons of free water. After their treatment cycle, the water quality often exceeded EPA drinking water standards, and the annual maintenance costs of their collection and treatment system averaged $898, or about three cents per gallon (based on their 90 gallon/day average usage). Cole and Townsend calculate in their report that if each of Tucson’s 250,000 single-family homes harvested 1,000 gallons annually, hundreds of millions of gallons could be conserved citywide.
Cole also appeared in Beyond the Mirage, a 2018 Emmy award-winning documentary about the future of water in the West. He spoke about the different ways to collect and store water, including rainwater harvesting and gray water recycling, saying “The day may come when we will have to get involved in multiple levels of rainwater and stormwater harvesting to use in our community.”