Sanctify Water( Stormwrack, p. 93)
You can call upon positive energy to momentarily transform normal water around you into holy water. This feat is often learned by the clerics and paladins of sea gods, as well as aquatic clerics of all stripes.
CHA 13, ability to channel positive energy,
By expending a daily turn undead attempt, you can infuse the water around you with positive energy, which has the same effect as holy water. All creatures in a 20-foot radius around you immediately take damage as though they'd been struck directly by a flask of holy water. The water retains positive energy for a number of rounds equal to 1 + your Charisma modifier, and deals damage each round. Creatures unaffected by holy water are similarly unaffected by this ability.