Rainwater Harvesting &
Condensate Recovery
New Tools for Sustainable Site
Development
By
Tom Barrett
May 2009

Green • Water • Infrastructure
Green • Water • Infrastructure
Green • Water • Infrastructure
Green • Water • Infrastructure
Green • Water • Infrastructure

Untapped Reservoir
Untapped Reservoir
Untapped Reservoir
Untapped Reservoir
Untapped Reservoir

How Much Rain Falls in Chicago?
January - 1.86" Image of Rain Falling
February - 1.58"
March - 2.59"
April - 3.28"
May - 3.75"
June - 4.08"
July - 3.39"
August - 3.38"
September - 2.91"
October - 2.65"
November - 2.09"
December - 1.88"
Total 33.44"

Thirty Year Average
Monthly Rain Fall
Chicago
(1971 - 2000)
5.00
4.50
4.00
3.50
3.00
Inches
2.50
2.00
1.50
1.00
0.50
0.00
January February March April May June July August September October November December
Month
Graph of Chicago Rain Fall

How Much Water Falls in Chicago?
2,500 sq. ft. Roof
January - 2,727 gallons Image of Rain Falling
February - 2,540
March - 4,130
April - 5,735
May - 5,268
June - 5,657
July - 5,470
August - 7,200
September - 5,096
October - 4,223
November - 4,691
December - 3,787
Total 56,525

How Much Water Falls in Chicago?
¼ Acre Residential Property
January - 11,880 gallons Image of Rain Falling
February - 11,065
March - 17,990
April - 24,982
May - 22,945
June - 24,642
July - 23,828
August - 31,363
September - 22,199
October - 18,397
November - 20,434
December - 16,496
Total 246,221

How Much Water Falls in Chicago?
3 Acre Commercial Property
January - 142,560 gallons Image of Rain Falling
February - 132,784
March - 215,876
April - 299,783
May - 275,344
June - 295,710
July - 285,934
August - 376,358
September - 266,383
October - 220,764
November - 245,203
December - 197,954
Total 2,954,654

How Much Water Falls in Chicago?
City Block
(660’ x 660’ – 10 acres)
January - 475,195 gallons
February - 442,610
March - 719,581
April - 999,267
May - 917,805
June - 985,690
July - 953,105
August - 1,254,515
September - 887,936
October - 735,873
November - 817,335
December - 659,842
Total 9,848,756

How Much Water is in Rain Event?
¼” Rain ½” Rain 1” Rain
2,500 ft. sq. 390 gallons 779 gallons 1,558 gallons
Roof
¼ Acre 1,697 3,994 67,789
Residential
Property
3 Acre 20,366 40,731 135,770
Commercial
Property
Chicago City 67,885 135,770 271,540
Block

What can we do with this water?
• Flush Toilets
• Wash Vehicles
• Clean Sidewalks
• Laundry
• Water the
Landscape

How Much Do We Use?
Daily Monthly Annually
Toilet - 19 gallons 570 6,840
Bathing - 15 450 5,400
Laundry - 8 240 2,880
Kitchen - 7 210 2,520
Housekeeping - 1 30 360
Total 50 1,500 18,000
The average household uses between 50 and 100 gallons of water
per person per day.

How Much Water Does a Landscape
Need in Chicago?
January - 0.00"
February - 0.00"
March - 0.68"
April - 2.01"
May - 3.95"
June - 5.89"
July - 6.99"
August - 6.07"
September - 3.87"
October - 2.08"
November - 0.63"
December - 0.00"
Total 32.17"

What is the Problem?
ET Rain Difference
January - 0.00" 1.75" 1.75"
February - 0.00" 1.63" 1.63"
March - 0.68" 2.65" 1.97"
April - 2.01" 3.68" 1.67"
May - 3.95" 3.38" -0.57"
June - 5.89" 3.63" -2.26"
July - 6.99" 3.51" -3.48"
August - 6.07" 4.62" -1.45"
September - 3.87" 3.27" -0.60"
October - 2.08" 2.71" 0.63"
November - 0.63" 3.01" 2.38"
December - 0.00" 2.43" 2.43"
Total 32.17“ 36.27" 4.10"

Evapotranspiration
(Chicago)
8
7
6
5
4
inches
Evaportation
3
2
1
0
t
ril
y
r
er
ly
ne
r
ch
ay
y
r
us
be
be
ar
be
ar
Ju
ob
Ap
M
Ju
ar
ug
nu
em
u
em
em
M
ct
br
-1
A
Ja
v
ec
O
pt
Fe
No
Se
D
Month
Graph of Chicago Evapotranspiration

Precipatation
(Chicago)
8.0
7.0
6.0
5.0
inches
4.0 Rain Fall
3.0
2.0
1.0
0.0
st
ril
y
r
er
ly
ne
r
ch
ay
ry
r
be
be
ar
be
gu
Ju
ob
Ap
ua
M
Ju
ar
nu
m
m
em
Au
M
ct
br
ve
ce
Ja
O
pt
Fe
No
De
Se
Month
Graph of Chicago Rain Fall & Evapotranspiration

ET vs. Precipatation
(Chicgo)
8
6
4
2
Rain Fall
inches
Evaportation
Difference
0
t
il
ry
r
r
ly
e
r
ch
ay
ry
r
us
be
be
be
be
pr
n
Ju
a
ua
M
Ju
ar
ug
A
nu
o
em
em
m
M
ct
br
A
te
Ja
ov
ec
O
Fe
ep
-2
N
D
S
-4
-6
Month
Graph of Chicago Rain Fall & Evapotranspiration

Landscape Ecology
Size the landscape to the
80% of the average rain
water production.
– Roof Runoff
– Hardscape Runoff
Balancing rain water to
landscape creates a
functional landscape that
utilizes the site’s water
production.

Stormwater Mitigation
Stormwater Mitigation
Stormwater Mitigation
Stormwater Mitigation
Stormwater Mitigation

Stormwater Mitigation
– Collection runoff near the
source
– Slow it down
– Soak it in
– Filter it
– Apply it to the landscape
– Create habitats

Peak Flow
(1 Acre Site)
Grass Field Roof
1 Year Storm 1.4 cfs 4.3 cfs
2 Year Storm 2.1 cfs 5.4 cfs
10 Year Storm 4.3 cfs 8.0 cfs
25 Year Storm 5.7 cfs 9.5 cfs
100 Year Storm 8.0 cfs 12.0 cfs
cfs – cubic feet per second

Peak Flow
(1 Acre Site)
Grass Field Roof
1 Year Storm 10.5 gps 32.2 gps
2 Year Storm 15.7 gps 40.4 gps
10 Year Storm 32.2 gps 59.8 gps
25 Year Storm 42.6 gps 71.1 gps
100 Year Storm 59.8 gps 89.8 gps
gps – gallons per second

Peak Flow
(1 Acre Site)
Grass Field Roof
1 Year Storm 630 gpm 1,932 gpm
2 Year Storm 942 gpm 2,424 gpm
10 Year Storm 1,932 gpm 3,588 gpm
25 Year Storm 2,556 gpm 4,266 gpm
100 Year Storm 3,588 gpm 5,388 gpm
gpm – gallons per minute

Peak Flow
(2,500 sq. ft. Roof)
Grass Field Roof
1 Year Storm 0.08 cfs 0.25 cfs
2 Year Storm 0.12 cfs 0.31 cfs
10 Year Storm 0.25 cfs 0.46 cfs
25 Year Storm 0.33 cfs 0.55 cfs
100 Year Storm 0.46 cfs 0.69 cfs
cfs – cubic feet per second

Peak Flow
(2,500 sq. ft. Roof)
Grass Field Roof
1 Year Storm 0.60 gps 1.85 gps
2 Year Storm 0.90 gps 2.32 gps
10 Year Storm 1.85 gps 3.43 gps
25 Year Storm 2.44 gps 4.08 gps
100 Year Storm 3.43 gps 5.15 gps
gps – gallons per second

Peak Flow
(2,500 ft. sq. Roof)
Grass Field Roof
1 Year Storm 36 gpm 111 gpm
2 Year Storm 54 gpm 139 gpm
10 Year Storm 111 gpm 206 gpm
25 Year Storm 147 gpm 245 gpm
100 Year Storm 206 gpm 309 gpm
gpm – gallons per minute

Change in Peak Runoff Flow
Before and after Development
250%
200%
150%
100%
50%
0%
1 Year Storm 2 Year Storm 10 Year 25 Year 100 Year
Storm Storm Storm
Stormwater Effects of Urbanization

Collection and Dispersal
Collection Systems
– Rain Barrels
– Downspout Collection
– Cisterns
Dispersal Systems
– Rain Gardens
– Bioswales
– Irrigation

Rain Barrels

Rain Barrels

Rain Barrels
• Collect a small
amount of water
– 50 to 300 gallons
• Can be
unattractive
• The water must be
used

Downspout Collectors

Downspout Collectors
Captures 90% of the rainwater

Cisterns
Above Ground

Cisterns
Below Ground

Putting It Together

Control Systems
Sensors plus Logic Circuits
Cistern Sensors
• High Water
– Disperse the water
– Alarm
• Irrigation Water
– Reserve for landscape
• Household Water
– Minimum if household water use
• Low Water l
– Pump protection
Irrigation System
• Soil moisture

Drip Irrigation Systems
90% Efficiency Rating

Expanding Stormwater Detention
Systems into Stormwater Retention
Small increase in size Image of Growing Plant
creates a large increase in
volume.
Small increase in cost
delivers a large volume of
water.
Mitigates the ¼” to ½”
rainfall events.

Condensation
Untapped Reservoir
Condensation
Untapped Reservoir
Condensation

HVAC Condensation
• ½ gallon per hour per ton
of air conditioning.
• 1,000 ton air conditioner
produces 8 gallons of
water per minute.
• Condensation production
occurs when the landscape
needs the water.

HVAC Condensation
• ½ gallon per hour per ton
of air conditioning.
• One ton of air conditioning
for every 700 sq. ft. of floor
space.
• One ton of air conditioning
for every 5,600 cu. ft. of
building volume.

Residential Condensation
• 8 to 15 gallons of water
per day.
• 60 to 100 gallons per
week.
• 250 to 450 gallons per
month.

Commercial Condensation
• 15 gallons of water per
minute.
• 360 gallons of water per
day.
• 2,520 gallons of water per
week.
• 10,000 gallons of water a
month.

Green • Water • Infrastructure
Green • Water • Infrastructure
Green • Water • Infrastructure
Green • Water • Infrastructure
Green • Water • Infrastructure

Untapped Reservoir
Untapped Reservoir
Untapped Reservoir
Untapped Reservoir
Untapped Reservoir

Questions?
• Green Water Infrastructure
• Strategic Planning
• Marketing
• Training
Tom Barrett
104 Ash Circle
Noblesville, Indiana 46062
(317) 773-3111
(317) 441-8703 cell
Tom.Barrett@JTBarrett.com