When we returned from Yowah in early October, we traveled 920km over two days - in solid rain.
Once home again we discovered the large storage box was not waterproof. Drat!
We use a tub for washing up and that was half-full of water! Amazing!
During our transit period when we lived in a small van, it was easy to see where the roof leaked - because we could watch the drips forming along the ceiling. It's a bit trickier to be sure about the storage box leaks. The box roof is made from two panels and it may be that water accessed the box via that seam. There was some sealant evident but Nick added another layer today. Fingers crossed that works!