Water harvesting for the sheep house.

Only about four weeks to go before the sheep come inside for the rest of the winter so have been fitting the new sheep house out with troughs, its the kind of rough woodworking that I'm good at, I'll never be a cabinet maker. I was once told that the difference between a joiner and a Carpenter was that a Joiner worked to the nearest millimeter whereas a carpenter worked to the nearest house.

The design is meant to provide an effective barrier and feeding trough. The length of the trough is important as pregnant ewes need lots of space to feed, 50cm (20 inches in N. America and Wales). Only one more job to complete, we need a water supply. Tapping into the water main is horrendously expensive so the plan is to capture rainwater from the roof.Here is where I have to revert to Imperial measurement, Seventy square metres (77 sq yds) of roof should harvest how much water?

If an inch of rain falls on an acre of ground that inch is equal to 22,610 gallons (27,154 US galls). this is where I have to open a spreadsheet! The roof area is 0.0159 acres so it receives 360 imperial gallons for every inch of rainfall (1617 litres for every 25mm rainfall).

So no shortage of supply its just a matter of finding a couple of containers that are big enough.