They are very waterproof, but liquid sits on top rather than being absorbed by top layer and not soaking through. It then tends to run off bib. I prefer polar fleece bib over towelling.
I Purchased two, then three pairs of these. I’m very satisfied that they’re true to label. They give me some peace of mind when my wife wears them and they’re easy to wash.
Far better than 2 pairs I bought previously because the secondary hem leg guardis now about 30mm wide on previous ones was about 5mm and far too narrow.