 The 600 square metres ( 6 @,@ 500 sq ft ) radiative condenser illustrated near the start of this article is built near the ground . In the area of north @-@ west India where it is installed dew occurs for 8 months a year , and the installation collects about 15 millimetres ( 0 @.@ 59 in ) of dew water over the season with nearly 100 dew @-@ nights . In a year it provides a total of about 9 @,@ 000 litres ( 2 @,@ 000 imp gal ; 2 @,@ 400 US gal ) of potable water for the school which owns and operates the site . 
