Is is clearly stated in the Qur’an that Riba is prohibited by Allah the Most High, He says:
“Those who swallow usury cannot rise up save as he arises whom the devil hath prostrated by (his) touch. That is because they say: Trade is just like usury; whereas Allah permits trading and forbids usury. He unto whom an admonition from his Lord comes, and (he) refrains (in obedience thereto), he shall keep (the profits of) that which is past, and his affair (henceforth) is with Allah. As for him who returns (to usury) – Such are rightful owners of the Fire. They will abide therein.” (Al-Baqarah, 275)
It is clear from this verse that Riba is Haram everywhere.
Money earned by mistake, before a person knows and understands the rulings of Sharia, should be given to Muslim charity institutions. Once a Muslim knows the ruling of Sharia, he/she must quit the prohibited practice and repent to God.
Hence, using interest money for electricity or water bills is prohibited as there is no difference between such and using it for food consumption etc.