Supplies are restocked as and when they are needed
I heard a tale - maybe apocryphal - that some units in the field were unable to be resupplied at times and had to resort to drastic measures to get fluids, i.e. drinking their own urine.
If - stressing the IF - this is the case, then surely either the Government hasn't got a handle on what's going on, or MoD hasn't, or MoD has and isn't telling the Government, or the higher echelon field commanders haven't a scooby's, or somesuch other failure of communications has occurred between the unit commanders on the ground and the MoD spokesman quoted above.
IF the above apocryphal story is true, then surely someone somewhere needs to make a decision to fix the problem - no water = no fit troops = no hearts and minds.