Rainwater Harvesting:

Using and Reducing the Water that Goes to Waste.

An Answer to Urban Water

Quantity and Quality Problems

By Steve Williams

©2012

Tree loss in the Atlanta metro area from 1974 to 1996 resulted

in a 33% increase in stormwater runoff (from each 2-year peak

storm event). This translates into an estimated 591 million

cubic feet of water or 4,420,987,013 gallons. Costs to build

engineered systems to intercept this runoff would cost $1.18

billion ($2/cubic ft. of storage) in 2001 dollars.

Data from the American Forests study

Urban Ecosystem Analysis, Atlanta, GA

Urban Ecosystem Analysis

The City of Atlanta

This translates to $85.9 million per year.

The total stormwater retention capacity of our urban

forest cover in 1996 was worth about $2.36 billion,

down from 1974's value of $3.54 billion.

Water Runoff from Development

Development in Atlanta, GA and surrounding counties

contribute to a yearly loss of groundwater infiltration ranging

from 57 to 133 billion gallons from 1982-1997.

American Rivers, Natural Resources Defense Council and Smart

Growth America

Report: Paving Our Way to Water Shortages:

How Sprawl Aggravates the Effects of Draught

August 28, 2002

The rest can be allowed to filter through the soil to recharge aquifers and

increase underground flows to replenish rivers, streams and estuaries.

If managed on site, some

of this rainwater which

could support annual

household needs of 1.5

to 3.6 million people, can

be captured in cisterns

(reservoirs).

Where is the

Water Going?

TRADITIONAL SOLUTIONS

Retention

Ponds

TRADITIONAL SOLUTIONS

Side

Walks

Sewers

Sewers

Streets

to

TRADITIONAL SOLUTIONS

THE EFFECTS

STREET FLOODING

THE EFFECTS

EROSION and LOSS

of TOP SOIL

THE EFFECTS

CREEKS OVERFLOWING

THE EFFECTS of

OUR CURRENT

WATERSHED MANAGEMENT

A rain harvesting technique that can store water for shortages,

reduce stormwater and replace potable water uses with non-

potable water.

CISTERNS

Treated water is an expensive resource.

By diverting rainwater during heavy rains, cisterns can store it for use

during draught, this will also reduce stormwater run off.

Technology is readily available and relatively inexpensive.

Rainwater is a healthier alternative to potable water for plants.

Rainwater collection is insurance for your plants.

Less than 50% of American household water usage requires the

purification of drinking water such as toilets, laundry and outdoor use.

Commercial and industrial uses provide use everyday.

REASONS FOR USING

CISTERNS TO COLLECT

RAINWATER

THE COMPONENTS

Floating Filter

Calming Inlet

Roof Washer

Pump

Overflow

First Flush

Controllers & Level Indicators

THE COMPONENTS

Floating Filter

Calming Inlet

Roof Washer

Pump

Overflow

First Flush

Controllers & Level Indicators

THE COMPONENTS

Floating Filter

Calming Inlet

Roof Washer

Pump

Overflow

First Flush

Controllers & Level Indicators

THE COMPONENTS

Floating Filter

Calming Inlet

Roof Washer

Pump

Overflow

First Flush

Controllers & Level Indicators

THE COMPONENTS

Floating Filter

Calming Inlet

Roof Washer

Pump

Overflow

First Flush

Controllers & Level Indicators

THE COMPONENTS

Floating Filter

Calming Inlet

Roof Washer

Pump

Overflow

First Flush

Controllers & Level Indicators

THE COMPONENTS

Floating Filter

Calming Inlet

Roof Washer

Pump

Overflow

First Flush

Controllers & Level Indicators

THE COMPONENTS

Floating Filter

Calming Inlet

Roof Washer

Pump

Overflow

First Flush

Controllers

THE COMPONENTS

How can this practice

reduce the effects of

out of control Stormwater?

STORMWATER

MANAGEMENT

By sizing the tank based on the roof area peak

events can be stored to reduce the run off

PEAK

FLOW

First Flush

The first flush is used to

capture the first 2-5% of

the water on the roof

that holds the

contaminants.

TMDL

REDUCTION

Technical Guidance: Stormwater Treatment Credit for Rainwater Harvesting

Systems

Revised September 22, 2008

Overview:

It is the policy of the NC Division

of Water Quality to enable and

encourage the use of rooftop

rainwater harvesting systems

(cisterns) to reduce stormwater

runoff pollution from an individual

site.

NORTH CAROLINA

STORMWATER

TMDL REDUCTION

Collecting and storing rooftop runoff, and

providing a consistent, dedicated, and

reliable end use, will reduce the volume

of runoff and enable the reduction in size

of other required stormwater treatment

systems on the site.

PEAK REDUCTION

In watersheds requiring nutrient removal

from stormwater, dedicated uses of the

collected rainwater or proper

treatment/infiltration can reduce

stormwater nutrient removal

requirements.

This policy establishes the credit that will be allowed in the NC

Division of Water Quality (DWQ) permitting programs that

consider impervious built upon areas (BUA) and that rely on

calculations of runoff volume and peak flow for sizing stormwater

Best Management Practices (BMPs).

NORTH CAROLINA

STORMWATER

Stormwater Treatment Credit for Rainwater Harvesting Systems

Revised September 22, 2008

• The cistern must be sized to treat the design

rainfall (ex. 1”, 1.5”, 1-yr 24-hr storm) from the

roof area directed to the water harvesting system.

• All stormwater collected must have a dedicated,

year-round. A water balance calculation must be

used to establish the dedicated use volumes and

rates.

• The overflow shall discharge flows in excess of

the design volume BMP flow for the 10-yr rainfall

event. It shall not discharge directly to impervious

surfaces.

• If a first flush diverter is used, the bypassed water

must discharge to a properly designed BMP

In order to receive credit,

the following criteria must be met:

NORTH CAROLINA

STORMWATER

There are possibly 45 stormwater utilities in Georgia,

I found 14 and 8 responded.

Athens Covington Decatur Duluth Gwinnett Henry County Rockdale County Roswell

GEORGIA

STORMWATER

Rain Barrels Cisterns Reduction BMP’s Ga Stormwater Manual 3%, 5%, 10%, 85% Set Amount of Years Reapply Total Credit No Credit Site Verification Photo Verification

Guidance Manual for Rainwater Harvesting as a Stormwater Best Management Practice

A Report of the State of the Practice and Recommended Guidance

by the EWRI Rainwater Harvesting Technical Committee

The goal of this report is to advance rainwater harvesting (RWH) as an urban

stormwater management best management practice (BMP) by providing

guidance to local governments seeking to implement RWH as part of their

stormwater programs.

•Specifically, the report describes

•RWH positive and negative impacts on the urban water budget,

•Local, state, and federal policies affecting RWH,

•Methods and tools for design,

•Ways to administrate, maintain, and finance programs,

•Approaches to provide public education and outreach to developers and

maintenance staff.

NEW RAINWATER

STORMWATER

GUIDELINES

• IAPMO-International Association of Plumbing and Mechanical

Officials

• IgCC-International Green Construction Code

• ARCSA-American Rainwater Catchment Systems Association

• Georgia Rainwater Harvesting Guidelines

Other guidelines that are available or in the process of being finalized

OTHER

RAINWATER

GUIDELINES

Georgia Stormwater Management Manual: Volume 1: Atlanta Regional Commission Wikipedia http://www.harvesth2o.com/ ARCSA: American Rainwater Catchment Systems Association Construction Resources is Britain's first ecological builders' merchant, and a center for ecological building. Urban Ecosystem Analysis, Atlanta Metro Area, Calculating the Value of Nature, AMERICAN FORESTS P.O. Box 2000 Washington DC 20013 American Rivers, Natural Resources Defense Council and Smart Growth America, Report Rainwater Harvesting for Drylands Vol. I&II Brad Lancaster www.HarvestingRain.com Jones, M. P. and Hunt, W. F. Rainwater Harvesting: Guidance for Homeowners. N.C. Cooperative Extension publication AG-588-11. Raleigh: N.C. State University

NCSU BAE Stormwater Engineering Group http://www.bae.ncsu.edu/stormwater

Rainwater Harvesting at North Carolina State University http://www.bae.ncsu.edu/topic/waterharvesting/

The Texas Manual on Rainwater Harvesting (2005, 3rd Ed.), Texas Water Development Board. Austin, Texas

Georgia Rainwater Harvesting Guide

American Society of Civil Engineers and Environmental & Water Resource Institute - Dr. Steven Burian U of Utah

and Dwane Jones NCSU

RESOURCES

404-234-1358

steve_williams@watermgt.com

Steve Williams