In episode 2 of Noragami, we see that when Yato's hand gets blighted, he can remove the blight from his body with water from the Shrine he sleeps at.
However, in episode 9 Hiyori successfully removes her blight with water from Kofuku house. Are there any criteria for the water that is used for cleansing a blight?
As said on the Wikia article on Blight:
Blight mark without phantom eyes can be cleansed by washing it away using purifying water obtained from shrines or natural springs. This method only works for a God that is injured by a phantom’s attack or a soul that is infected from a wounded God.
Even though Kofuku does not have a shrine, I guess the water at her home qualifies as "purified" owing to it being her abode, and her being as famous/worshipped as the Seven Gods of Fortune.
Either that, or she has stored some "purifying water" at her home for dealing with blights like in the case of Yato.
I forgot what episode it is but Daikoku mentioned that the water they get in the house is straight from the shrine.
