I am about to try the same thing. The darkroom requires us to supply our own consumables, which is fair enough. I was planning on using soft drink bottles of around the 1.25L capacity as the 8x10 trays I plan on using 95% of the time have a capacity of around 800ml.

Most of the other darkroom users use the PET soft drink bottles as well. They're pretty leak resistant. Just make sure they can't be mistaken for anything drinkable!