Water Tank Watch

It hadn't rained for weeks. The dam was low and muddy, and the grass crunched underfoot.

"How much water is left in the big tank?" asked Suzy.

Little Thunder climbed up beside the round green tank. A gauge on the side had a little float that went up and down. "The arrow is pointing halfway."

"The tank holds ten thousand litres when it's full," said Spike. "So half full is five thousand litres."

"That sounds like heaps!" said Little Thunder.

"Let's work out how long it'll last," said Suzy. "How much do the animals drink each day?"

They made a list. The cows drank the most. Cairo the cow said, "I drink about fifty litres on a hot day."

"There are eight cows," said Spike. "Eight times fifty is four hundred litres. Plus the chickens and the dogs, about a hundred litres more. So five hundred litres a day."

Little Thunder did the sum slowly. "Five thousand litres, and we use five hundred each day. That's... ten days!"

"Ten days isn't very long," said Suzy, worried.

Just then, thunder rumbled in the distance. Dark clouds rolled over the hills.

"Rain!" shouted Little Thunder.

Big drops began to fall. They pattered on the shed roof and gushed down the gutter into a pipe. The pipe led straight into the tank.

"The roof catches the rain," said Spike. "Every millimetre of rain on our shed roof gives us about a hundred litres."

The rain poured all afternoon. When it stopped, Little Thunder checked the gauge. The arrow was nearly at the top!

"Nine thousand litres," said Suzy. "That's eighteen days of water."

Cairo sighed happily. "Every drop counts."

"Even the drops on my nose," said Little Thunder, shaking his curly head.