Harvesting rainwater to irrigate your garden is probably one of the
most cost-effective and sustainable decisions you can make. In
times of water restrictions, this is also a smart counter measure to
take. Rainwater is free and if you don’t use this resource, it simply
flows away in the stormwater system and disappears. For every
100 square metres of roof surface area, you can potentially harvest
100 litres of water if it rains just 1 millimeter! So, a downpour of
10mm on your roof could yield 1 000 litres of water.