//Dave, do the math. You take a whiz far more often than a " full meal deal".//
Provided the cistern size remains the same (though somewhere it mentions 6 litres as a full flush which is hopelessly inadequate) then Dave is correct. If the same number of flushes are performed, some at half and some at full capacity it cannot reduce the water requirement to less than half. It’s probably because Dave employs more than one “Math” in his calculations that he is able to come up with the correct answers.
“The common household toilet is one of the main offenders when it comes to water wastage.”
Incorrect. By far and away the biggest offenders when it comes to water wastage are the water suppliers, some of whom lose up to a third of their product through leaks.