texas; urban rainwater harvesting for landscape irrigation - austin energy
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Texas; Urban Rainwater Harvesting for Landscape Irrigation - Austin EnergyTRANSCRIPT
Urban Rainwater Harvesting for Landscape
Irrigation Dick Peterson
Environmental Program
Coordinator
Austin Energy Green Building
www.austinenergy.com/go/greenbuilding
Rainwater Through The AgesRainwater harvesting practiced for over 4,000 years in desert of southern IsraelAncient Roman had cisterns and aqueductsEarly 1900’s farms and ranches had cisterns
Current resurgence of rainwater collection Lady Bird Johnson Wildflower Center
Currently72,000 gallon capacityhave plans foranother 25,000 gallons
Many Caribbeannations mandaterainwater harvesting
Why Collect Rainwater?
Rainwater pH is almost neutralPlants love itRainwater does not have dissolved minerals from the soilOr chemicals from water treatment plantsHarvesting reduces erosionReduces water bill – you do not use as much expensive potable water on your landscape
In Texas, rainwater harvesting systems are sales tax exemptTax Code Section 151.355(1) provides an exemption for the recycling system if purchased on or after September 1, 2001.
Sec. 151.355. WATER-RELATED EXEMPTIONS. The following are exempted from taxes imposed by this chapter: (1) rainwater harvesting equipment or supplies, water recycling and reuse equipment or supplies, or other equipment, services, or supplies used to reduce or eliminate water use….
First Flush “Poor Man’s Roof Washer”
Components
PVC pipe with fittings running to the ground with a screw on cap at the bottom for clean out
First 8-10 gallons collects debris from roof and gutters --diverted by first flush before tank inlet
First Flush “Poor Man’s Roof Washer”
Components
PVC pipe with fittings running to the ground with a screw on cap at the bottom for clean out
First 8-10 gallons collects debris from roof and gutters --diverted by first flush before tank inlet
First Flush “Poor Man’s Roof Washer”
Components
PVC pipe with fittings running to the ground with a screw on cap at the bottom for clean out
First 8-10 gallons collects debris from roof and gutters --diverted by first flush before tank inlet
First Flush Filter & Inlet Piping
ComponentsPVC Drain-Waste-Vent Fittings
Recycled drums can be easily converted into rainbarrels
Sunshine Community Gardens Rainbarrel Clinic
Salvaged drums can be left as is or painted to better blend with the
landscape
Horizontal, vertical and with an ornamental, decorative rain chain
Recycled drums come in various shapes, sizes and materials
City of Austin Water Conservation Program
www.cityofaustin.org/waterco n
Tanks are available in many sizes and configurations
Simple System Options
Simple System Diagram
How about a pond tank?
Drinking Water Systems
Drinking water systems require more equipment and maintenance
Drinking water systems require more equipment and maintenance
From “Rainwater-Collection Systems” by Peter Pfeiffer
Fine Homebuilding Magazine
Drinking water systems require more equipment and maintenance
Good source of tanks are “feed and ranch” stores
5,000
2,500 3,000
305 300 550
To reduce algae, tanks should be black, green, covered, or painted
Tall configuration 500 gallon tank
Low configuration of a 500 gallon tank
Sometimes a “rain barn” is built to provide more roof area
2,500 Gallon Tank
Tank inlet must be lowest point in the collection piping
2,500 gallon system on a high school portable classroom
Zilker Botanical Garden Master Gardener Greenhouse
American Botanical Council has 2-850 gallon collection tanks
8 years old
Liner System helps avoid rust
American Botanical Council 10,000 gallon fiberglass storage tank
American Botanical Council 10,000 gallon fiberglass storage tank
American Botanical Council
American Botanical Council
Coriolis Effect
Location and access may dictate size of tanks
Two 1100 gallon tanks cost more than one 2500, but allow access to garage
A 10’ x 10’ garden shed can collect 60 gallons in just a 1” rain
750 gallon fiberglass tank
Austin’s first “modern” harvester
Hugh M. “Bud” Kane
H. E. B. Grocery Store in Austin
46,000 gallon Ferro-cement tank
Sunset Canyon Pottery Studio
77,000 gallon Ferro-cement tank
Typical Underground Cistern
37,500 gallon Ferro-cement tank
From “Rainwater-Collection Systems” by Peter Pfeiffer
Fine Homebuilding Magazine
Wooden Tanks
500 gallon “TimberTank”
How much will rainwater harvesting cost?
It really does vary...Do you already have gutters?If not, what type will you install?Type and size of tankWill you use a pump?Pad construction
This is NOT how to do it!
ComponentsRoof Type
Any roof will doMetal is the ideal roof - smooth and non-absorbentComposite, wood shingles, asphalt…all absorb water and will break down over time
Gutters30 cents per foot for plastic up to $15 per foot for copper
ScreensScreens are not necessary unless your house has a lot of tree cover
ComponentsRoof Washer
From “Rainwater-Collection Systems” by Peter Pfeiffer
Fine Homebuilding Magazine
ComponentsRoof Washer
$300-600 container with 30 micron filter water must pass through filter before filling tankIf not cleaned regularly
breeding ground for bacteriawill keep water from entering tank
not necessary for non-potable systems
ComponentsBarrels
Purchased or recycled barrelShould be painted to keep out sunlight and prevent algae growth
ComponentsPolypropylene Tanks
$.35 to $1.00 per gallonMost commonEasy to installShould be black, green or painted
ComponentsConcrete or Ferro-cement tanks
$.35 to $1.00 per gallonDurableCan be buried
ComponentsMetal Tanks
40-60 cents per gallonShort life span – rust, except with special liners
ComponentsWooden Tanks
$2.00+ per gallonIdeal for remote locations, pack in the
piecesCan be dissembled and movedAvailable up to 2,000,000 gallons!
Components
Stone TanksVery expensiveDifficult to maintain
ComponentsPumps
$200-600install pump as close to tank as possibleprotect from freezingin-tank float switchin general 3/4 quarter horsepower is sufficient It will allow you to pump water 400 feet
Maintenance With a first flush system you will want to clean out the PVC after every rainfallIf you have screens, clean them after a rain when there has not been any rainfall for a period of timeMost people who have installed their systems over the past 5 years, have not had to clean the tank of debris
Bt-Biological Mosquito Control
Whisky is for drinkin'… Water is for fightin’ over!
Water is a precious resource…
Use it wisely…
Harvest rainwater!
Mark Twain
Austin History Center, St. Edward’s cadet straddling Lake Austin
Urban Rainwater Harvesting for Landscape
Irrigation Dick Peterson
Environmental Program
Coordinator
Austin Energy Green Building
www.austinenergy.com/go/greenbuilding