Rain in Penang is very localised. It can rain in Balik Pulau on the other side of the island, or Batu Ferringhi, further around the coast, or in the south of the island, but not rain in Pulau Tikus, where I am. In fact, it can rain a few streets away, and not here.
But in this area is was dark and threatening at 7:30 this morning, and pouring at 8:30.
So my simply rain collection system has enough to water the garden for three days after it stops raining.