Water leaking in drivers footwell

[pete127]

Having pulled the carpet to treat what I thought was a little surface rust under the front passenger seat I was treated to the full horror of a pool of water,soaking wet carpet backing and a flintstone floor!

Have chopped out and replaced all the bad stuff and am now trying to identify where the leak is coming from.It's running down the drivers side wheel well from undertake dash.Have had the watering can on the windscreen anion the door seals but they seem ok.Are there any common places or problems I should be checking out?

Thanks in advance.