Have you noticed that your water heater isn’t able to produce the volume of hot water that it once did? One of the commonest causes of this is a broken dip tube, inside the tank. Replacing the dip tube is an easy and inexpensive fix. This shows a step by step example of this repair. Edit: Several people in the audience suggested that I missed the opportunity to install unions at the connection points, which would have allowed easier replacement of the water heater in the future. They are right about that and I would recommend that be done also.
This video is posted for entertainment purposes, and is not a comprehensive instructional guide. I am not a professional plumber, and so if you intend to do this yourself you will need to study this topic in more depth from multiple sources before trying it yourself. The accuracy of the appended information is not guaranteed, and you need to check your local plumbing code before proceeding with any attempted repair. Any misadventure resulting from your attempt to accomplish any plumbing repair is your responsibility.