texas; urban rainwater harvesting for landscape irrigation - austin energy

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