Long before breaking ground for their home, located overlooking Grape Creek, Tim and Patty Elliott knew they would be installing a rainwater harvesting system. When they moved from water rich Houston to Blanco County they first lived in Johnson City while preparing to and building their new home in the hills. That is where they encountered confirmation of their plans when they discovered that water from the public water supply was much more expensive than in Houston.
Had there been any doubt (which there wasn't), that discovery, reflecting the relative scarcity of groundwater here, sealed their decision to rely on rainwater.
Tim designed the rainwater system after much research. An important design decision early on was integration of an enclosed "rain barn" with the house structure. This decision resulted in several benefits.
First, it provided a relatively low cost way to expand, significantly, the collection surface while relying on a single guttering and PVC collection system (a total of 7,000 square feet for the house and attached garage and water barn).
Second, the crushed granite floor of the water barn made an excellent pad for his four 5,000 gallon tanks. By designing the barn with a height to accommodate the tanks provided the third benefit, enclosed parking for the travel trailer that had served as home for the final 5 months of construction.
Building the rainwater system along with the house allowed the Elliot's another advantage; easy burial of the PVC used to connect the gutters to the tanks. The exposed PVC is unobtrusive, painted brown to match the trim on the house, as may be seen in the photos of the front and read of the home.
Another feature to note is that Tim chose to have more downspouts than are normally employed. This small added expense in PVC will likely pay big dividends in collection efficiency during our heavy downpours; those gully washers that sometimes result in gutter overflow on rainwater systems not as well drained as this one.
Anticipating a common experience of rainwater harvesters, Tim planned the tank overflow part of the system thoughtfully. In virtually all systems, when the rains continue after the tanks are full, the water begins to flow from the overflow pipes and onto the ground as waste.
In most cases the system owners watch with thoughts of "where could I put another tank?" In the Elliott's system, overflow pipes for all the tanks are joined and terminated outside the water barn with a flap check valve, to prevent critters from crawling in. The valve is positioned so that, in the future, that water can be easily accessed to fill a small pond or other useful applications.
One of two approaches is generally used to assure that no bacterial contamination is present in water intended for potable use. One technology is exposing the water to UV light prior to entering the pressure tank; this is the one we see most frequently in Central Texas.
The other is injection of ozone. Both approaches are effective but each has somewhat different requirements for safe operation.
Tim has employed a novel approach to assure that no contamination occurs.
In addition to an ozone generator attached in-line as the water feeds into the pressure tank (a typical approach), a second system component serves to inject ozone, on a regular schedule, into all of the water in storage. Using a swimming pool filter device and small demand pump, he cycles the water from the storage tanks through the filter where a second ozone generator is attached.
He has this mechanism controlled by a timing device so that the process occurs regularly but during the wee hours of morning when there is little or no water demand.
In addition to the collection and storage system for the house, a small system is installed on the barn. A 3,000 gallon tank stores the water collected from the 1,000 square feet of barn roof. Although intended for a garden to be, this tank connects to the house system and water can be transferred if the need should arise.
Several aspects of the Elliott system design reflect the thinking and research of Dr. Kent Butler, Associate Dean of Architecture at UT Austin. Dr. Butler has done extensive work on the challenge of incorporating rainwater systems into suburban developments where space and esthetics are more restrictive factors than in many rural settings.
Those considering systems in urban or suburban residential locations may wish to examine the Elliott system for ideas.
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