Available on Project MUSE and JSTOR. Online access to Contemporary Literature is available as part of the Project MUSE collections. All back issues of Contemporary Literature beginning with Vol. 1, 1960 are available online through the JSTOR digital archive.
Many manufacturers recommend water heater anode replacement every two to four years depending on the hardness of the water that passes through the tank and the quality of the water heater lining.
believe it or not, we've actually replaced water heaters that were over 40 years old! Depending on whether your on city or well water, how many people in the house, and size of the water heater, I'd expect you should be able to get at least 12 years - most are about 18 years when we replace them.