?

Trying to find how big a holding tank needs to be to catch all the rain
off the roof of a new clubhouse of 50 metres x 20 metres.

Mike,

The average for the UK is usually taken as about 30 inches (approx 0.75
metres) a year.

This will give an annual volume on the clubhouse roof of approx 750 cubic
metres! The tank will need to be 10 by 10 by 7.5 metres! It might be
better to calculate the volume of water needed during a drought of X days
duration for its tank might be smaller but still meet requirements.

For those who do not know it, the IW has metered water and the domestic cost
is 58.6p per cubic metre without counting the wastewater charge, so Mike's
not talking of saving peanuts if Southern Water charge the same figure for
watering a bowls green.

If a more accurate figure for the average is needed I suggest a letter the
editor of the Isle of Wight County Press.

Regards

Geoff on the Island.