Keep in mind the chance of these Curing Doom is not 100%, infact during PM 2-5 i got doomed and went threw the last 5 waters i had without any curing it... i died ><
Check Hallowed Water. It has a much higher success rate at removing Doom than Holy Water. More expensive, but they can turn an annoying Doom death into a win. When you also consider the wasted unsuccessful Holy waters, Hallowed waters might not be much more expensive when comparing how many waters it takes per successful removal.