A word of advice for you Squeaky.
Go out and invest £12.00 on a 200W aquarium heater. Put in whatever it is you store your RO water in, because you will get to next week or whenever it is and intend to go to work without having thought ahead the day or night before and find all your RO is frozen and unpumpable.
And then you'll expect us to put up with your self-pitying whinging simply because you dont plan ahead.
I got a heater in my van tank too if you can stretch to £24.00