Virtually all residential water heaters employ at least one sacrificial anode to protect the inside of the water heater from rusting out. Through a process called galvanic corrosion, the anode rod is consumed while the tank walls remain intact - this is the reason it is called SACRIFICIAL. The rod is depleted in service and must therefore, be routinely replaced to keep protecting the tank from failing. If it is not replaced in a timely fashion, the tank will start to rust leading to an unwanted failure due to leakage, requiring replacement of the tank.
For best results and continued protection, we recommend the sacrificial anode is inspected routinely and replaced about every 6 to 9 years or when your warranty has expired (whatever comes first.) As a general rule of thumb and at minimum:
"WHEN YOUR WARRANTY IS UP, CHANGE YOUR ANODE ROD OUT!"
This picture shows actual sacrificial anode rods removed from traditional residential water heaters. They are shown from brand new to completely depleted, exhibiting different amounts of wear after varying years of protective service.
Sacrificial Anode Rod - The Key To Tank Longevity
1 - A new sacrificial anode rod
made of magnesium.
2 - 3 years of service.
35% of the sacrificial anode’s
magnesium is already depleted.
The rough surface indicates it is
working well. The rod is still
viable and should provide
several more years of reliable
protection.
serviceable condition
3 - 6 years of service.
70% of the magnesium content
is depleted. It is still working
well, but is near recommended
limits for wear and exposed
core wire. It should work for a
couple more years, but for
best results, replacement
should be considered soon.
replacement recommended
4 - 8 years of service.
90% of the protective layer of
magnesium is exhausted from
this combo rod and most of the
core wire is exposed. A definite
candidate for immediate
exchange.
replacement required
5 - 12 years of service.
100% of the protective cover of
magnesium is stripped away
and even part of the core wire
has rusted through and broken
off. This was removed from
a tank that developed a leak
and had to be replaced just
shortly into its twelfth year.
replacement - too late!
Had the anode been changed
out regularly, this water heater
could have provided many,
many more years of service.
Anode rod replacement recommendations
- 75% of protective material is depleted, or
- More than 1/3 of the core wire is exposed, or
- Average outside diameter is less than 3/8"
NOTE: The anodes shown here are from 40 gallon water heaters employed in multiple person households. Results will vary depending on tank quality, temperature set point, water usage rate, mineral content of the water, type and quantity of anodes installed and whether a water softening method is employed.