Is it permissible or forbidden to pay an amount of money to an employee in a government agency to supply water to an orphanage's farm, especially since water is scarce for them?

If the company provides water for free and you are entitled to it, and you paid money to the worker to obtain your right, then there is no blame upon you, and the sin is upon the worker. This is not considered a bribe, for a bribe is given to invalidate a right or establish falsehood. However, if the company does not provide water and the worker wants to trick you and supply you with it in exchange for money, then this is forbidden and considered a bribe. The Prophet, peace and blessings be upon him, cursed the briber, the bribed, and the intermediary.