In message . com,
" writes

I was about to post that Kay and you did it for me! We are careful
where we buy our watercress from, locally, because Edward (mine that
is, not your Edward) remembered from his student days, someone who got
liver fluke through eating w.cress from a stream in Oxfordshire.


Liver fluke require both sheep and snails (and you to eat a tiny snail
with your watercress) so if you start with safe commercial watercress
and there are no sheep near your pond you should be OK.

Wild watercress isn't safe to eat raw but makes very good watercress
soup.

--
Sue ] PhD