The FACT is 411A, pilots are purveyors of their craft/trade.
We agree to sell our flying "skills" to certain purchaser. In return, the terms and conditions of payment are directly conditional upon the skills supplied - pretty much like any contracted tradesman you employ.
If the purchaser then finds that he is UNABLE to make the agreed payment, the vendor is likewise at liberty to adjust the level/degree of quality service supplied.
The 1.5 liters of H2O provided for a long haul flight again draws your envious derision, 411A, so allow me to quote from an M.D.'s (that's a Doctor of Medicine, 411) reference manual wrt to the REQUIREMENT of water, at SEA LEVEL fo the human body to maintain Nutrition, Diet, and Wellness:
Water is an essential nutrient that is involved in every function of the body....It is necessary for all digestive, absorption, circulatory, and excretory functions, as well as for the utilization of the water-soluble vitamins. It is also needed for the maintenance of proper body temperature. By drinking an adequate amount of water each day - at LEAST eight 8-ounce glasses (2.05 liters) - one can be assured that his bodyhas all it needs to maintain good health"
So in light of KNOWN PROFESSIONAL MEDICAL ADVICE, the employer (in this case B.A.) is knowingly and wilfully depriving their crews of LESS than the MINIMUM amount of water determined by Doctors as necessary for maintaing their health.
Withdrawal of payment entitles the provider to supply/withdraw his level of service!