water storage

G'day Vanners, I have two 85l water tanks under the van and it takes forever to fill them. I have purchased two different hose extensions but still get airlock. Is this normal and does anyone have a fix. Any feedback is appreciated.

Just did a few days away free camping in our new Caravan and was pleased with our setup, but thought it would be nice to have some extra water storage in the tow vehicle. We already carry about 60l in plastic "jerry" cans and decided it wold be nice to have another 80l to 100l of water storage...