Plastic holding tank smells on the outside?

[jlcarreiro]

I have a 81 Sabre 28 with an old if not original holding tank. When I lift the settee there is definitely a smell... hoses when touched do not smell, when I rub the outside of the tank there is a definite odor.
Do plastic holding tanks eventually need replacing?
TIA everyone.

[peghall]

It's extremely rare for a plastic (PE or PP) tank to permeate...I only know of one "case" and it occurred when the tank was new, due to a mfr'ing error. However odors from other sources can attach themselves to the outside of tank. Permeated hoses are the most common source...I know you said yours are fine when touched, but I recommend that you do the "hot wet rag test" on all of 'em including the vent line: Wet CLEAN rags in HOT water--as hot as you can handle. Wrap each section of hose a clean rag...let it cool, then remove each rag and smell it. If you can't smell anything on that rag, that section of hose is ok...but if you can, that hose has permeated. If they all pass the test, but have recently been replaced, the previous hoses could have transferred odor to the lockers/areas they passed through and everything in them.

Other possible sources: a leaking tank or hose fitting or perhaps a spill when hoses were replaced. A leaking macerator pump...even the bilge if it's in serious need of REAL cleaning.

Finding the source may not be easy and you have my sympathy. I spent two months trying to find the source of odor under my v-berth...I was sure it could NOT be hoses...it hadn't been 90 days since I replaced them. But finally testing 'em was the only thing left to do...and "sho nuff" as we say in the South, those brand new hoses had already permeated.

--Peggie

[LittleWing77]

And if you haven't got a copy of Peggie's book, JL - get one!

The New Get Rid of Boat Odors
https://www.amazon.com/New-Get-Rid-B...dp/1892399784/

LittleWing77