Gray water tank fabrication question

[4x4 explorer]

I'm getting ready to fabricate a gray water tank for a expedition camper and would prefer to build it using aluminum. However, someone raised the question regarding gray water being corrosive to aluminum. Can any one with experience verify or refute that. I thought about it and, if necessary, I could slosh a liquid tank sealer in the completed tank so gray water never comes in contact with aluminum. Any help would be appreciated.

[Mickldo]

I'm getting ready to fabricate a gray water tank for a expedition camper and would prefer to build it using aluminum. However, someone raised the question regarding gray water being corrosive to aluminum. Can any one with experience verify or refute that. I thought about it and, if necessary, I could slosh a liquid tank sealer in the completed tank so gray water never comes in contact with aluminum. Any help would be appreciated.

Aluminium should be fine. I'd use 5083 marine grade alloy and fully weld it. The 5083 doesn't fold very well so I'd get each corner welded ratehr than fold any of it. The other thing to do is not to use differing metals with the tank. In other words don't screw brass fittings into the system. Just weld alloy tubes into the tank and hoseclamp the hoses on. If you do need to use stainless screws to hold a sender unit on or something use a product called Duralac on the threads to isolate the two different metals.

[4x4 explorer]

Thanks for the info. Most of the camper is already aluminum, so I knew not to mix metals. I just wanted to confirm that nothing in normal gray water would be corrosive to the aluminum tank. Particularly nothing that might be added by municiple water supply. I may still slosh sealer around inside of completed tank as insurance.

[chasespeed]

Put a zinc in there, on a fitting that you can pull and check each year.. that will save your aluminum.

Chase

[4x4 explorer]

Chase... thanks for that suggestion. Can you elaborate on how the zinc works. Also best source, plumbing supply?

[Lynn]

Chase... thanks for that suggestion. Can you elaborate on how the zinc works. Also best source, plumbing supply?

Basically the zinc is a 'sacrificial' metal. It 'draws' the corrosion, so that the aluminum doesn’t corrode (as much).

Chasespeed mentioned putting it someplace accessible. That way it can be periodically checked and replaced.

Check marine supply stores, like West Marine and such. Actually, I think I’ve seen them in Walmart’s boat supply section, as well.

[4x4 explorer]

I'll do that and thanks for the additional information and explanation