hi everyone.just a question if anyone can help ...

hi everyone.just a question if anyone can help me plz.bubby has not been wanting his bed bottle.i have the cooled boiled water in the bottles in the fridge.wen he wants a bottle i heat the water then add the formula.if he doesnt drink any of it (like tonight) can i put it bak in the fridge then use it in the morning.i think it should b ok as only the water has been heated but just wanted some advice please.thanx in advance.