Sacrificial anode (water heater)

A sacrificial anode is a rod of a more reactive metal (usually magnesium or aluminium) fitted inside a storage water heater's tank to protect it from rusting. It works by *galvanic corrosion*: because the anode metal is more reactive than the steel tank, it corrodes in its place — it is literally sacrificed so the tank isn't. Over the years the rod dissolves away, and once it's gone the tank itself begins to rust and will eventually leak (usually the real reason an old heater 'suddenly' fails). In Dubai's hard water anodes deplete faster, so checking the anode every few years and replacing it when it's mostly gone is the cheapest thing you can do to add years to a water heater — far cheaper than a new tank. A persistent rotten-egg smell from the hot water can also point to an anode reacting with bacteria in the tank. Swapping an anode (and flushing the tank while it's open) is a straightforward job for a plumber in Dubai; makers such as Rheem specify the anode type and replacement interval for their heaters.