What’s That Odor?

Proper connections and quality hoses prevent the sanitation system from taking over your boat. Want an easy way to find out if your boat’s sanitation hoses have been permeated? Soak a clean rag in hot water, then wrap it around a hose and leave it there for three minutes. Place the rag in a sealable sandwich bag and leave the boat with it. When you open the bag, if it smells like effluent, the hose has been permeated.


With careful planning, quality materials and good installation practices, there’s no reason why a boat’s sanitation system can’t be free of odor. Often, though, a system’s woes stem from when the vessel was built or when the system was installed or refit.

Many leakage problems, and the resultant odors that are sure to follow, can be traced to poor installation practices. Make certain the boat’s hoses are installed over properly sized pipe-to-hose adapters. The connection between the hose and its adapter should be clean and the surfaces free of scratches, nicks and other damage, as they all present a path for leaks. Never install a hose over threaded plumbing; the threads form a helical path for fluid to follow. Because few flexible sealants are designed to resist immersion in effluent, the interface between hose and plumbing should be made dry, although threaded connections should be coated using an appropriate pipe-thread sealant. Double clamp hoses using solid band-style hose clamps.

Hose used for sanitation should be specifically designed for effluent; choose the hose with the longest permeation warranty.

Caution should be taken when selecting a sanitation hose. Many PVC-based sanitation hoses prohibit the use of alcohol, which is often used for winterizing purposes. Once exposed to alcohol, PVC hoses turn gummy and can be prone to permeation. And if you’re buying a new boat, ask what sort of hose was used. Some builders use the cheapest they can find, and it may quickly become permeated. Ideally, where possible, rigid PVC pipe should supplant hose; it essentially lasts forever and is permeation proof.


Poor installation practices can also lead to odors. The most common problem is a dip or a valley in an effluent hose. In some cases, these are unavoidable, but trim excess hose to eliminate low areas that can trap liquids. In such spots, odor permeation can set in with a vengeance.

Another flaw in sanitation-system design worthy of mention is the holding tank. Ideally, holding tanks should be made from such nonmetallic materials as vinylester, epoxy-based fiberglass or polyethylene. Aluminum and even stainless steel aren’t well suited to containment of caustic effluent, as they suffer, respectively, from poultice and crevice corrosion.

Finally, the hose connections on holding tanks should be located on a horizontal surface rather than on a side or bottom. Side and bottom connections ensure that a section of hose will always be submerged in effluent — with predictable results.


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