Lack of hot water may have 2 causes. First, the dip tube that forces incoming water to the bottom of the water heater tank so that hot water can be drawn off the top may be broken. Or secondly, if you have an electric water heater, the lower heating element may not be operating properly. This would cause only half of the water to be heating up. In any case, the true reason for your lack of hot water can only be determined by an expert. Our professionals at Home Alliance Plumbing Service will gladly be at your service.