Leaking water from Vauxhall Corsa 1.7d Breeze (S Reg)?

I am leaking water quite extensively, having to top up the radiator quite regularly.

It seems to be leaking from somewhere near the fan belt, (looking from above) on the left side of the engine but quite well hidden from view.

Could this be the water pump? If not what else could it be?

Either way, does anyone know what kind of a job would be required and how much it may cost?

Thanks in advance,

Jon.