My father decided to fix the faucet
without turning off the water at the mains.
He thought if he were quick enough,
shrewd enough; if he kept his
eye on the ball and his hand in,
he could pull it off without the need to
empty the system, waiting while the water
drained away. He was wrong.

Open a valve without due caution
and all of the pressure built up behind
seizes the chance to attack the breach,
overwhelm it in a moment.
There was a lot of swearing, and a
family bucket-line of bailers and towel-bearers
pressed into service to fight the flood,
then sop up the sorry, soggy mess.