Aluminum holding tank expected lifetime

[Don]

Peggy:As the posting implies, I'm wondering what the "averge" or "expected" lifetime might be for an aluminum holding tank. I realize that there are a multitude of variables involved, but I thought you might have some insight.I have a 1993 37.5 on the Ches Bay (although formerly cruised down south.) So far no leaks or apparant corrosion on areas I can inspect visually. That said, I know they don't last forever based on your and others' postings here at HOW. Any thoughts on when I should "bite the bullet" and replace it?As always, thanks.

 

[fred miller]

Mine is age 10.

Don;My aluminum tank is 10 years old on my 35.5. I pump it out regularly and flush it with fresh water. I check the welded seams too. Last year I had the seams rewelded, not because they leaked but as a precautionary measure given the bad reputation of aluminum and because I was in the "are' doing some hose change work.I'm a fan of aluminum over poly. Odor permeates poly after awhile . .run a damp rag across a poly tank that has been in use a year or two and take a whiff.Aluminum does not allow the odor to permeate. . .but it does need more attention as I noted.We sail now in salt water [Atlantic City area] having come down from the Great Lakes. Only time will tell the effects of salt water. If I had to replace the tank I would go to metal again . .maybe stainless if I could. Fred Miller S/V M Squared

 

[Peggie Hall/Head Mistress]

Lifespan isn't based on date of installation, but

on when the tank first went into service holding waste. It could have been on the boat for 15 years before it was ever used. And there are no absolutes, only averages. The first leaks usually occur in a weld, at a seam or a fitting, in 2-5 years. 10 years is about the time it takes urine to eat through the sheet metal, usually the bottom of the tank. If the inside of the tank was coated with epoxy, the above MIGHT be extended 50%. As for when to replace it...when the first leak appears. Till then, just keep an eye and your nose on it and pressure test it every spring.

 

[Peggie Hall/Head Mistress]

Fred, a thick-walled poly tank will NOT permeate

Mine had been on my boat--under the v-berth--for 16 years when I bought the boat, and was still odor-free after 21 years when I sold the boat. Any odor that can be rubbed off the outside of a plastic tank was transferred onto the outside of the tank from another source, usually from permeated hoses.