Help! Our cistern just cracked, but according to the letting agency this is not an emergency so won't be dear with til office hours. Apparently it will flush if we just throw a bowl of water down the bowl? To my mind this would cause a water build up? Any advice?
Water build up where? Stick a bucket or other container under the crack if water is still coming out. Yes, you can flush the loo by chucking a bucket of water down the pan. It won't cause any problems though may not be as efficient as the flush.