Rainwater Harvesting in the Texas Hill Country
Source: Aditi Agarwal
Increasing water demands and supply shortages statewide will result in a water deficit of more than one-third of the projected total water demand by 2060. Much of this deficit, particularly in the Hill Country, can be attributed to rapid population growth and resulting water supply demands.
A significant portion of this water deficit may be remedied through water conservation practices, including rainwater harvesting. A pathway to sustainable water management may be to largely live off the water which falls upon – and can be recycled or reused on – building sites. This approach is required under the Living Building Challenge, which is a new building standard that pushes the sustainability envelope well beyond LEED. This strategy may also accommodate development without incurring the costs and other liabilities of large-scale water transfers or building new reservoirs. Thus, it may most cost efficiently enhance sustainability of water resources.
With funding from the Texas Water Development Board, The Meadows Center for Water and the Environment and their collaborative partners are currently investigating such a strategy using building-scale rainwater harvesting systems, a facilities design and management approach, and assurance of backup supply for entire developments. The feasibility of this water supply strategy will be evaluated for several communities in the Texas Hill Country where wells typically provide water supplies and the aquifers supplying those wells are under stress. If found to be feasible, this strategy could be employed in any part of the state receiving sufficient rainfall.
Courtesy of www.nativeplantsalvage.orgA modeling process will determine the size of the building-scale facilities, which includes the roofprint (collection area) and cistern (water storage) volume. Both interior and exterior water use can be reflected in the model. The impact of reusing wastewater derived from the captured rainwater, instead of the rainwater directly, to defray exterior demands can also be reflected in the model. 
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Defining adequate water use profiles within building design concepts will be important to cost-efficiently incorporate an adequate roofprint and cistern volume.
The outcomes of this investigation will inform the process of creating rainwater harvesting water supply systems across Texas. The key deliverables will include: (1) a report detailing various aspects of designing, installing, implementing, and maintaining building and development-scale rainwater collection strategies; (2) recommendations for where and how this strategy might be profitably employed; (3) a “tool box” including the model and instructions for its use; and (4) development and delivery of a webinar package.
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Stakeholders interested in this approach may include:
- Developers
- Planners/engineers
- Architects
- Builders
- The public sector at state and local levels
- Rainwater harvesting practitioners
- Water companies
- End users of the developments which employ this water supply strategy, to the extent that sustainability of their water system is a factor in their choice to buy into such developments
Texas Water Development Board Rainwater Project
Rainwater Harvesting Systems as a Development-wide Water Supply Strategy -- Summary Report (PDF)
For additional resources regarding rainwater harvesting, please view the Resources for Environmental Information in Central Texas handout (PDF)