Steven replied:

Lars,Water certainly does go off in plastic containers and much quicker in clear plastic, however at least with clear you can see the algae growth and take preventitive steps.
Example I carry water in the centre console in clear Gatorade 600ml. bottles, if I fill with Melbourne water it starts to smell/taste after 4 or 5 days; if I fill with tank water I'm lucky to get 2/3 days. Why? City water has chlorine and copper sulphide and other chemicals added.
I did a Simpson Desert crossing in 2000 and carried water ratchet strapped in the rear footwell of my Jackaroo in 10L.(easier to handle than 25's) clear plastic with no probs. Go for clear and wrap each one in black plastic. Also carry some Puritabs (or a film container of stabilised chlorine granules, much cheaper)in case you get some iffy water, (boil to remove chlorine taste. hope this helps, safe travelling, Steven P.