Swimming pool in both footwells!

[Richy182.]

I'm currently having a problem with a leak in both footwells. There is a lot of water coming in through the bulkhead. I have taken up all the carpet and foam both sides and the water is about 1 cm deep in some places. Under the seat there is a lot of grit and mud as if it has come in from the road somewhere. I checked my scuttle panel and found the drivers side drain was blocked, but it is still leaking and all the foam on the bulk head is dripping. The windscreen looks fine, I'm just stuck on where the water is coming from as it's not a small leak! Any help would be appreicated!