Tap water from an US EPA regulated supplier (most everyone except trailer parks and very small towns in rural areas) is supposed to be slightly passive to protect the plumbing. We use aluminum sulfate (alum) to purify water and chlorine is forbidden now as a disinfectant except to purge the pipes once or twice a year.
ChlorAmines are used to disinfect, but it is corrosive to common rubber toilet flappers, so better grades of rubber are now common. Chlorine was banned because it reacts with trace organics to make compounds that may cause cancer. Ozone is also used, but sparingly because of the cost to make it. Reverse osmosis is also common, but costly, so it is reserved for water otherwise too salty for direct use.
In the US, water tanks with longer warranties simply have bigger sacrificial anodes. One of the disadvantages of aluminum is that it swells when it corrodes, so you may not be able to unscrew it to replace it. As long as you don't drink the water that goes through the hot water tank, the aluminum from the anode or lining shouldn't be a health hazard.
Just pull cold water from another source and heat it if you want to make tea or coffee, or cook with it.
Magnesium can give you the "runs" but it makes a better anode.
