2002 Vauxhall Corsa water getting in floor very wet

As you suggest check / clear drains below w/screen at bulkhead , usually get blocked .If stiill having probs. after that check , get back for more help.

My Daughter recently bought a 2002 corsa and had the same problem. The carpet and undercarpet were soaking wet in the drivers footwell. We took it back to the garage three times before they agreed to strip the car down until they found the problem. The mechanic (who was really patient and just as puzzled as us)removed the carpet to dry then stripped the car. When he did this he found that there was a bolt hole on the bulkhead(?) which did not have a bolt in place. The mechanic used a water jet to spray water around this hole and found that the water trickled down into the car and through a gap behind the brake pedal and into the footwell of the car (they actually seen the water do this). The mechanic filled the bolt hole and sealed the bolt he had put in place. They put the car back together and SUCCESS! We have had the car back for about 5 weeks now and not one drop of water has come through the car. I know this may sound extreme but the mechanic had tried everything he could think of before resorting to this. He even looked at corsa car manuals and could not find any reference to this bolt hole so did'nt know it even existed until he stripped the car down I'm glad he did it though as the car is now completely dry and what was even better was he never charged for all of his work. Hope this helps you. Good luck and hope this helps