Friday, September 22, 2023


Will water left in bottom of RV’s water heater corrode the tank?

Dear Dave,
After a camping event, I usually pull the water heater anode to drain and flush the tank, leaving the tank close to empty. I have noticed that the tank never completely empties. Will the bottom of the tank corrode if left in this condition, since the anode is not submerged in the residual water? —Gregory, 2021 Alliance Paradigm 310RL

Dear Gregory,
You most likely have a Suburban water heater, since it has an anode rod, and like most water heaters, the drain valve is not the lowest point on the tank. This will leave a couple of inches of water and most likely calcium, rust, and lime floating in the bottom. Technically, yes, it can corrode the metal of the tank without the anode rod in place; however, I believe it would take a very long time and would depend on the hardness of the water.

Something that you can do it flush out the tank with a water heater flush wand that you can get at Amazon here.

This hooks up to a garden hose and really churns the deposits in the bottom of the tank and flushes them out. You will still have water sitting in it, but it will be cleaner. If you have access to treated water, and even softened water, it would be best as that could sit in the bottom and not deteriorate the tank.

Use a shop vac

Another option would be to use a shop vac and an attachment that reduces down to hook a 12” hose on the end. You can find one here.

I would suggest using the clear braided 1/2” hose with a worm clamp, as this will be flexible enough to bend it to the bottom of the tank and allow you to see when no more water is being drawn out. Since it typically comes in a roll, it already has a natural bend to enable it to get to the bottom. Typically, the drain plug is 3/4”, so the tube would fit.


 You might also enjoy this from Dave 

When do you replace the water heater anode?

Dear Dave,
How do you know when it’s time to replace the water heater anode? —Timothy

Read Dave’s answer.

Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

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Dave Solberg
Dave Solberg
Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. He has been in the RV Industry since 1983 and conducts over 15 seminars at RV shows throughout the country.



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