CLB Journal

Spring 2010

Made Between Heaven and Earth

One of the most important lessons that I have learned on the Browning Ranch is that rainwater collection is a sustainable water supply for the Texas Hill Country. This experience comes to me first hand as my wife Colleen and I have lived solely on rainwater captured off our roof for the past five years. During that time, the climate has been exceptionally dry. I mentioned in my posting from Fall 2009, that over a 23 month period from October 2007 until September 2009, only 23 inches of rain fell on the Browning Ranch. This drought is now recognized as the second driest period on record for central Texas. Several water wells - the most common source of residential water for the area - went dry, or the water became unfit to drink. Meanwhile, my 20,000 gallon collection system supplied by 3,500 square foot roof never dropped below 50% capacity. Colleen and I were amazed by this experience and grateful to be spared the discomfort of some of our neighbors.

Much of my work over the past eight years on the Browning Ranch has focused on hydrological investigations, especially into surface and groundwater interactions. This experience leads me to believe that groundwater is not a sustainable water source for the ever-expanding Texas Hill Country population. Much of this area gets its water from the Middle Trinity aquifer, which is estimated to capture only 4-5% of the annual rainfall as recharge. The Texas Water Development Board projects steep declines in Middle Trinity well levels over the next 50 years, and they consider it to be one of the most stressed aquifers in the state.

Rainwater collection does not work everywhere. Obstacles such as rainfall patterns and airborne toxins can make residential collection cost prohibitive. Homes in the north-east USA might need extra filtration capabilities to remove industrial pollutants, while homes in the desert southwest might need larger storage tanks to make use of the monsoonal rains that come once per year. Most of the residents in the central USA could consider rainwater collection a sustainable alternative where rains are seasonal and industry is sparse. This is especially true in Texas where water is so limited.

Rainwater collection is an ancient practice. We can document humans capturing rainwater for the past 3,000 years in meso-America, the Mediterranean, and the Orient. Examples such as the rainwater-supplied Roman atriums, the aqueducts of Malta, the Palace of Knossos on Crete, or the Sunken Palace in Istanbul, show us that throughout our history, rainwater collection has provided us the drinking water that is essential for our survival.

Many of the plants in central Texas have adapted to enable the capture and storage of more rainwater. The Ashe juniper (Juniperus Ashei) for example, has an oil gland at the base of each leaf that creates a bond between the leaf and a water droplet. Since the growth of the tree is often like a funnel, these water droplets will travel down the branches and main trunk to the shallow root system below. Similar adaptations to dry conditions can be seen in several other plants and animals throughout all arid environments. For example, in the Atacama Desert in Chile receives imperceptible rainfall yet supports over 550 species of plants that obtain the majority of their water supply from the moisture-laden air (fog) that frequents the area. These plants are proof that life can be sustained by collecting water before it hits the ground.

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This Blue agave, like our house, survives on capturing rainwater.

According to Richard Heinichen at Tank Town (www.rainwatercollection.com) in Dripping Springs Texas, a rainwater collection system will capture 550 gallons per 1,000 square feet of roof per 1 inch of rain. When the students of the University of Texas - School of Architecture undertook the Design.Build.Texas project that resulted in the design and construction the Manager’s House on the Browning Ranch, the roof was oversized to produce more shade on the exterior and more surface area for rainwater collection. They constructed 3,500 square foot roof that can collect almost 2,000 gallons for each inch of rainfall. Water-conserving appliances and a hot-water circulation pump enable our family of two - Colleen and myself - an average consumption rate of 2,000 gallons per month - the equivalent of one inch of rainfall per month.

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The single-pitch roof on our house makes for an easy rainwater collection surface to maintain.

The design of our collection system resembles a very wide ‘U’ made out of sealed PVC water pipe. One of the uprights is connected to the house at the bottom of the gutters (1). The other upright is connected to the storage tank (3). Since the elevation of the upright at the house is higher than the other upright at the storage tank, water will go down the pipe at the house, underground for 150 feet, and then rise up into the tanks. The first 200 gallons of collected water is diverted into a separate storage tank (2) that is drained after each rain. This eliminates gutter debris from the storage tanks containing the potable water.

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This diagram come from Richard at Tank Town and shows the stages of rainwater collection

We do not have to use electricity to get water into the storage tanks. Head pressure alone provides the needed energy. When we need to draw water, a very efficient, ‘on-demand’ pump pulls water from the storage tank through the filtration system (4/5) and then pushes the water throughout the house. Our water is filtered through a 5-micron sediment filter, then a 3-micron charcoal filter before it enters our ultra-violet light purifier that disinfects the water.

Yes, there is maintenance that must be performed in order to ensure a safe drinking water supply. I estimate that I spend one hour per month on changing filters and pressure-washing the gutters, but this maintenance responsibility is a small price to pay for peace of mind of knowing that Colleen and I can control the purity of our drinking water.

And the water is fantastic! Richard Heinichen calls it ‘Cloud Juice - Made Between Heaven and Earth’. Since the water never comes in contact with the ground, it is naturally metal, mineral, and chemical-free. There is no lime residue in the dishwasher and we never need to clean our hot-water heating element.

Most importantly, this last drought proved that rainwater collection is economically a better source for residential water. The 20,000 gallon system at my house that never dropped below 50% cost us $11,000. This price is very comparable, if not less, than the cost of drilling new water well. Most Texas Hill Country residents prefer to drill at least 400 feet in order to find a stable underground water supply, and drilling prices often start at $15 per foot. Large pumps are needed to raise this water up the surface. These are considerably less efficient than the pump for our rainwater system which moves water along a horizontal grade.

Sustainability is becoming a primary goal in all of our lives these days. This is not a fad but an increasing necessity everywhere on our crowded planet. Harvesting water from the sky is an appropriate, and now a tested, technology for those of us who live in drought-prone Central Texas.