Just about every iron we have had (steam) eventually leaks water, apart from
my wife denying she ever drops them what causes this?

If you lie the iron flat, as in hot plate face down it leaks water from the
hot plate steam holes, it eventually stops and then ironing can proceed. The
water reservoir probably hols around half pint and it probably leaks a
quarter of this before it stops.

The irons are cheap enough to replace bust just wondered if there is a cure,
to date I have never dismantled one. or indeed if anyone else has had this
problem.

thanks