Corrosion is the biggest problem in any system that uses water and metal together. There is a chemical reaction that occurs between the water and metal that is really unstoppable, however there is a way of slowing the corrosion and rotting down.The Anode:The anode is a rod shaped item that is made from elements such as magnesium and zinc that have a lesser resistance to the corrosive action that exists in a plumbing system. This means that it will start to corrode and rot away far quicker than the cylinder walls, which is a good thing as a rotten water storage cylinder has the potential to do some major damage should its integrity fail.Position:The anode usually sits in the top of the cylinder passively and is secured with one large nut and sealing washer. Because the anode is rotting, the tank damage will be greatly reduced. Its actual condition cannot be seen from the outside of the cylinder. Therefore it must be isolated and drained. Removal and Replacement:Anodes come in many shapes and sizes, so you must have the details of your whole system to ensure that you get the buy one. The information should be on a tag screwed to the heater. The anode is quite easy to replace. Isolate the power and the cold-water feed. Unscre the hexagonal bolt holding the rod.Take out the anode rod and replace with a new one. A Clerkenwell Plumber can fit an anode. Fitting should be done in reverse. Use Teflon tape on the thread of the fitting to stop leaks. Lastly:Restore water and power to the water heater and turn on.TIP:Twice a year you should visually inspect the anodes condition, as this is a good guide to replacement. Clerkenwell Plumbers know about anodes.