I have recently moved into a house and have found a butyl-lined pond at the
bottom of the garden with very little water in it. I have filled it but
find that the water level is falling. Not being experienced with ponds I
cannot tell if this is normal evaporation or a leak.

What rate of surface level fall would you expect to be normal for a pond
that is:
- in Wiltshire in England
- in shade
- about 4 square meters surface area
- no plants

thanks

Davy