Digging the secondary drainage ditch certainly helped - although I couldn't go too deep as the oil line was underneath. I think I will make that permanent.

The submersible pump was useful although a more powerful one would be better. Maybe an investment for the future to share with neighbours who are in the same boat...

The wet and dry Karcher vacuum is now doing a very good getting the remaining water out. And it is cleaning the carpet at the same time !