I am running a 5e campaign where my players own a Keep. On the surrounding property there is a pond, about 25 ft in diameter and 15 ft deep. My player's level 14 Cleric wants to turn the pond into Holy Water, he believes that this will give him unlimited holy water.
In the player's handbook it says"A cleric or paladin may create Holy Water by performing a special ritual. The ritual takes 1 hour to perform, uses 25gp worth of powdered silver, and requires the caster to expend a 1st-level spell slot" and Holy Water comes in flasks which suggests that 25gp is used for 1 pint of water.
How long and how much money will it take him to turn the whole pond Holy?
Will the pond dilute, as in the already Holy water loosing potency, if it takes him multiple days?
What about dilution due to rain?
If you could figure this out for me I would appreciate it
Best Answer
It is impractical to make the pond Holy using the ritual.
Assuming that the pond is perfectly cylindrical, it has a volume of 7,363 cubic feet. Google claims that such a volume is equal to 440,633 pints. All of the flasks listed on PHB 152-3 contain 1 pint, so if we assume that the ritual makes 1 pint of holy water, it would take as many hours to make all of that water Holy according to the PHB ritual.
A cleric of any level can spend at most 16 hours a day doing the rituals, because they have to spend at least 8 hours a day resting in order to get their spell slots back. At that rate, it would take 75 years and about 11 million gp worth of silver to turn the entire pond into holy water.
Unless I've made a serious math mistake somewhere, this order-of-magnitude calculation shows that it doesn't make sense to turn a large body of water into holy water.
However, the cleric does have the Divine Intervention class feature (PHB 59):
It seems to me that making a pond full of holy water would be within the purview of this feature, though it's ultimately up to you as the DM to decide.
There are no rules for potency.
I could not find any rules that dictate whether or not Holy Water retains its powers if diluted. Therefore, it's probably up to you as the DM to determine this.
What's the point?
Currently, in the rules, holy water doesn't have too much importance; it's a somewhat weak attack against fiends and undead, and it's a component of some spells.
I think that it's likely that your cleric player wants to accomplish something specific with the holy water. You should ask him what he wants to do with all that holy water, and then work with him on how he can accomplish that particular goal, instead of getting hung up on specifics like this. I find that focusing on intents and goals, rather than whether particular methods are impractical or not, tends to have better results at the table.