The above chart gives an approxomate number of gallons a home/business

could collect over the course of a year.
Roof Size
 
 
 
 
 
 
(Sq. Ft.)
35
40
45
50
55
60
1000
21,615
23,560
26,505
29,450
32,395
35,340
2000
41,230
47,120
53,010
58,900
64,790
70,680
3000
61,845
70,680
79,515
88,350
97,185
106,020
4000
82,460
94,240
106,020
117,800
129,580
141,360
5000
103,075
117,800
132,525
147,250
161,975
176,700
6000
123,690
141,260
159,030
176,700
194,370
220,590
7000
144,305
164,920
185,535
235,600
226,765
247,380
8000
164,920
188,480
212,040
235,600
259,160
282,720
9000
185,535
212,040
238,545
265,050
291,555
318,060
10000
206,150
235,600
265,050
294,500
323,950
353,400
Rain Fall (Inches)
Rain averages and watershed facts.
This chart shows monthly rain fall averages in the Metro Atlanta area over the past 12 years.

In addition, totals of each year, 12 year averages of individual months and the past twelve year average.
 
Jan.
Feb.
Mar.
Apr.
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Total
1996
8.26
3.82
6.42
2.91
2.12
1.7
2.14
4.66
4.32
0.89
3.22
4.14
44.6
1997
5.65
7.93
4.28
4.28
3.36
3.91
4.71
1.32
4.83
5.12
3.34
5.05
53.78
1998
5.83
7.1
5.12
5.12
1.23
3.58
2.93
5.54
4.45
0.26
1.97
1.9
45.03
1999
5.34
1.97
1.14
1.14
4.42
5.83
3.43
1.26
4.19
2.41
3.34
2.21
36.68
2000
4.89
1.26
2.63
2.63
1.86
1.11
2.7
4.03
4.91
0.88
5.02
2.62
34.54
2001
2.77
3.61
3.3
3.3
3.31
6.69
2.54
1.03
2.19
0.79
0.87
2.22
32.62
2002
5.35
2.54
1.83
1.83
3.52
2.81
2.59
0.77
6.39
5.94
5.36
5.23
44.16
2003
2
3.51
3.44
3.44
9.94
7.34
5.35
3.48
2.41
1.49
4.17
2.69
49.26
2004
2.84
4.6
2
2.8
2.58
5.99
2.2
3.63
13.65
2.19
7.26
4.82
54.56
2005
2.57
5.58
4.36
4.36
1.98
2.91
14.63
8.28
0.007
1.98
2.91
3.67
53.237
2006
5.1
5.5
2.48
2.48
2.86
5.8
1.31
8.66
3.31
3.04
4.39
3.08
48.01
2007
3.95
2.63
1.79
1.79
2.05
3.66
1.85
3.48
2.92
2.47
0.96
4.78
32.33
12yr avg
4.55
4.17
3.23
3.01
3.27
4.28
3.87
3.85
4.46
2.29
3.57
3.53
44.07