Rainwater Harvesting - An Overview Hari J. Krishna, Ph.D., P.E. Founder & Past-President, ARCSA Commissioner, City of Austin - RMC Austin, Texas
What is Rainwater Harvesting?
What is Rainwater Harvesting? It is the collection and storage of rainwater for beneficial use
Why do we need to harvest rainwater?
Why do we need to harvest rainwater? To address current and future water needs and demands
Global warming raises water shortage risks in one-third of all U.S. counties More than 1,100 counties in the continental United States will face higher risks of water shortages by 2050 as a result of global warming, and increased water demands (Tetra Tech/NRDC, 2010)
Fourteen states face extreme risk of inadequate water supplies by 2050 High-risk areas include parts of Arizona, Arkansas, California, Colorado, Florida, Idaho, Kansas, Mississippi, Montana, Nebraska, Nevada, New Mexico, Oklahoma and Texas (Tetra Tech/NRDC, 2010).
Colorado Water Conditions (April 16, 2013) 69% of the state in moderate and severe drought 25% of the state in extreme drought A few areas in exceptional drought (U.S. Drought Monitor)
Techniques to increase water availability Reduce demand through conservation and / or Increase water availability through Rainwater Harvesting
Types of RWH Systems Active RWH Systems - Collection of runoff from Roofs Cisterns, Rain barrels, Gutters, Filters, etc Passive RWH Systems - Collection of runoff from Land Surfaces Less complex, less expensive
RWH - Global Perspective USA, Canada, Mexico, Australia, India, China, Japan, Taiwan, Thailand Germany, U.K., France and The Caribbean Islands
RWH in North America Canada - Nova Scotia, Toronto, Vancouver U.S.A. - Texas, Ohio, Kentucky, North Carolina, Virginia, Oregon, Washington State, Hawaii, and other States U.S. Virgin Islands Mexico
What are the components of a RWH system? Minimum: Roof Gutter System Roof Washer / screen Rain barrel or Cistern
Additional components for indoor use Pump Filtration - Cartridge filters Sediment Filter, Activated Charcoal Filter Disinfection Ultra Violet Light and/or Reverse Osmosis
Lower Colorado River Authority 3 x 6,500 gal. cisterns
Lower Colorado River Authority 11,600 gallons
Advantages/Benefits of Rainwater Zero Hardness (Soft Water) ph neutral / slightly acidic Na-free for salt-free / low sodium diets Helps utilities in reducing peak demand Helps utilities in delaying water distribution systems Reduces demand on groundwater pumping Helps in reducing storm water flows Reduces NPS pollution
When is RWH most suitable? When no other water supply is available Unsatisfactory groundwater conditions - Inadequate quantity or poor quality Expensive to provide piped water supply Rainfall distributed throughout the year When a self-reliant, conservation-based lifestyle is preferred
RWH System Management Design and Provide adequate storage Conserve water / limit water use Indoor Use Provide regular maintenance for filters and UV Identify a backup water supply for emergencies
What is the cost of a RWH system?
What is the cost of a RWH system? Depends on the size of the system < $500 - over $10,000 Complete system for a typical home: Guttering, 10,000 gallon cistern, roof washer, pump, filters, and UV light - Approx. cost $ 9,000 (cost similar to well drilling and water treatment)
Utilizing RWH systems Landscape Irrigation, Fire Protection, Water for Livestock, Vehicle washing, Domestic animals and wildlife Toilets, Water Features With treatment - Showers / Laundry /swimming pools Potable use / kitchen Bottled Rainwater
Incentives for RWH State of Texas sales tax exemption on RWH Equipment Austin, San Antonio and other Cities - cash rebates for Rainbarrels and RWH systems, Rainbarrels sold at a discount through cost-sharing by towns and cities
Texas Manual on Rainwater Harvesting Published by the Texas Water Development Board Available on the TWDB website www.twdb.tx.gov and ARCSA website www.arcsa.org
ARCSA American Rainwater Catchment Systems Association Founded in 1994 in Austin, Texas to promote Rainwater Harvesting Non-Profit Professional Organization Currently has over 700 members Offers many educational programs
ARCSA Conferences Nine conferences held so far 10 th conference will be in Austin in Nov 2013 Details on ARCSA website
Thank You Questions? Hari J. Krishna hk_arcsa@yahoo.com