Apparent water air lock

On our 2nd day with our "new" caravan, having returned after 17 years, I thought that having empted the aquaroll, that I had created an airlock and I was unable resolve it. This meant the inconvenience of pouring water into sinks rather than use the taps. I tried all sorts of solutions without success and eventually phoned the retailer from whom I'd bought the caravan. He quickly identified the problem as a floating and twisting inlet pipe which is particularly prevalent at low temperatures. A neighbour helped out with a length of specially cut domestic waste pipe, solving what is an inherent problem, apparently! Why don't either the caravan or water carrier manufacturers provide a solid pipe to ensure that the water is collected from the bottom of the container? Huge thanks to my neighbour for his assistance, whoever you are!