[mykalberta]

Most airlines will use the potable water for tea and coffee and the warm towels if the airline does them. I cant think of one that uses the potable water for in-service consumption.

I tend to think they werent properly serviced at the airport which is why they were using the potable water.

The other possibility is that alot of these airlines will be serviced and loaded with food/water etc in Canada for both trips. So if the down trip consumes more than expected the return wont have as much.