Young Black Haired Girl Strips Her Black Dress On The Roof With A Rainwater Tank

Rainwater collection from roofs can be calculated using the following formulas:
• 1 inch of rain on a 1,000 square feet (93 m2) roof yields 623 gallons (2358 litres) of water; or
• 1 cubic foot equals (12 inch by 12-inch (300 mm) by 12-inch (300 mm) cube) equals 7.48 gallons; or
• 1 millimeter of rain on a 1 square meter surface yields 1 litre of water.