Hi Guys I have a 1997 Carver 405MY in the UK. I have constant urine smell from around both holding tanks. I have cleaned and flushed the tanks with clean water a number of times and used various off the shelf tank cleaning products and replaced the stern tank hoses but can't get rid of the smell. We have only used the heads for urine, no solids over the last 14 years. Could the plastic tanks themselves be the problem? Any advise would be welcome.
Those old Roto-cast plastic tanks are pretty good if supported well. Without support they can crack after lots of flexing on their own, like in a carver. Then, Roto-cast plastic tanks were built for a purpose, Cost-reduced (cheap). After all, 29 years from a Cost-reduced plastic tank is pretty good. Next ideas; Restricted vent lines. Splits in the tank where hose plastic hose barb screw in. Leaking macerating pump, fittings, valves and the tank cracked where this stuff screws into the bottom of the tank. Bad shower sumps (it can stink of pee also). Bad hoses forward. Ensure your bilge vents are clear. Get a big pump-up sprayer, fill it with cheap white vinegar, Spray everything in the bilges with it. Including under the deck plates. Around the head base also.
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