Volume of Rainwater you’ll get
= Rainfall in mm * Catchment area in sq.mt * Filter output efficiency
* For Annual water savings, know the annual rainfall of your place in millimeters. Take the DROPS filter efficiency as 0.90 (i.e. 90%). Estimate all the areas from which the rainwater flows to the Filter and add them to get the catchment area [Area in sq.mt = area in sq.ft / 10.764]
A basic chart showing various cities with a 30*40ft catchment area
City
Bengaluru
Chennai
Hyderabad
Mumbai
Pune
Ahmedabad
Dehli
Kolkata
.
Agartala
Bhopal
Chandigarh
Cuttack
Guwahati
Imphal
Jaipur
Jammu
Kochi
Lucknow
Madgoan
Patna
Ranchi
Shillong
Vijayawada
~Annual Rainfall
1000
1400
850
2200
850
775
775
1800
.
2000
1100
1000
1500
1650
1350
600
1400
2800
850
2800
1050
1400
2000
1000
Water you get
1,00,334 L
1,40,468 L
85,284 L
2,20,735 L
85,284 L
77,760 L
77,760 L
1,80,602 L
.
2,00,670 L
1,10,367 L
1,00,334 L
1,50,501 L
1,65,550 L
1,35,450 L
60,200 L
1,40,470 L
2,80,940 L
85,384 L
2,80,940 L
1,05,350 L
1,40,470 L
2,00,670 L
1,00,340 L
Equivalent Tankers
17
24
15
37
15
13
13
30
.
34
19
17
26
28
23
11
24
47
15
47
18
24
34
17