When you use a 33% lye concentration, you're already using a "water discount" based on how many people choose to define it. But "water discount" is only meaninful if you also know the "full water" point from which the discount is taken. Unfortunately, there is no consistent definition of "full water" and thus of "water discount".
Many people say something like, "I took a 10% water discount" and stop at that, because they don't realize there are several common starting points from which to take the discount. A common assumption is full water is 28% lye concentration, but that is only one of the several definitions I've found.
I'd like to see "full water" and "water discount" go away. They're not very helpful.
More in my article:
Soapy Stuff: Water in soap