Although here in Tucson we live in the desert, we know that when it rains it pours- especially during monsoon season. Below are two charts. The first shows the average rainfall in Southern Arizona and how many gallons of rainwater per month that can be collected from a 1000sq. ft. home. As you can see, a 1000 sq ft. home collects an astounding average of 7800 gallons of water a year with rainwater harvesting. The second chart shows the amount of water your home can collect based on the amount of rainfall and square footgage of your home. For example, a 2000 sq. ft. home collects about 1247 gallons of water with just 1" of rainfall. How much water could you collect from your roof?

Average Tucson Temperatures and Precipitation Month Avg. High Avg. Low Average Precipitation Rec. High Rec. Low Average gallons of rain captured for 1000 sq. ft January 66 33 .84 89 9 524 February 70 36 .80 97 11 499 March 74 40 .80 97 17 499 April 82 44 .22 104 24 137 May 90 53 .24 111 28 149 June 99 62 .35 116 38 218 July 99 70 2.54 114 52 1585 August 97 68 2.69 113 50 1678 September 94 62 1.39 111 38 867 October 85 50 1.12 103 20 698 November 74 39 .55 94 15 343 December 66 33 1.07 86 8 667 Total 12.61 7864

Average Rainfall Collected from a Roof
Inches of Rain	Sq. Ft. of Roof	1000	1500	2000	2500	3000	3500	4000
12.5		7792	11687	15583	19479	23375	27271	31167
12.0		7480	11220	14960	18700	22440	26180	29920
11.5		7168	10752	14337	17921	21505	25089	28673
11.0		6857	10285	13713	17142	20570	23998	27427
10.5		6545	9817	13090	16362	19635	22907	26180
10.0		6233	9350	12467	15583	18700	21817	24933
9.5		5922	8882	11843	14804	17765	20726	23687
9.0		5610	8415	11220	14025	16830	19635	22440
8.5		5298	7947	10597	13246	15895	18544	21193
8.0		4987	7480	9973	12467	14960	17453	19947
7.5		4675	7012	9350	11687	14025	16362	18700
7.0		4363	6545	8727	10908	13090	15272	17453
6.5		4052	6077	8103	10129	12155	14181	16207
6.0		3740	5610	7480	9350	11220	13090	14960
5.5		3428	5142	6857	8571	10285	11999	13713
5.0		3117	4675	6233	7792	9350	10908	12467
4.5		2805	4207	5610	7012	8415	9817	11220
4.0		2493	3740	4987	6233	7480	8727	9973
3.5		2182	3272	4363	5454	6545	7636	8727
3.0		1870	2805	3740	4675	5610	6545	7480
2.5		1558	2337	3117	389	4675	5454	6233
2.0		1247	1870	2493	3117	3740	4363	4987
1.5		935	1402	1870	2337	2805	3272	3740
1.0		623	935	1247	1558	1870	2182	2493
0.5		312	467	623	779	935	1091	1247
Click here for a printable PDF.