As per an old copy of the OM C the following flights only have a total uplift of 60% water.
EK001,002,003,004,005,006,017,018,073,074,380,384, 385,412,413(trans Tasman) 761,762. Other flights are topped up with more water and some 100% as no potable water is uplifted at the destination station. It is the same process with different fleets and indeed airlines. Weighing in at 1KG per litre, it is an expensive non-revenue generating weight. With out aux tanks 1700KGs of dead weight (in revenue) terms increases the fuel burn on each and every flight. The cost of extra fuel to carry the extra weight will mount up over the year and the EK team has a profit target to beat. Hence a look at which routes typically consume less water will lead to those flights having less uplifted.