Rupert (W.Yorkshire) wrote:
[...]

My suggestion is to build the pond you want in terms of shape, depth etc and
fill it with cobbles and rocks amongst which you can have the odd water
feature. At a future date you can start to remove the odd cobbles etc etc.

That's the most elegant solution: in some situations it could even look
better than a pond, but I bet the stones would go green. I've had
experience building and maintaining a pond in a school: we used the
steel grid suggested by others. 6" weldmesh is strong, and you may be
able to scrounge a piece from a friendly building site. It goes rusty,
though.

--
Mike.