Smelly Head Hoses: How to Test, Choose and Replace Sanitation Hose

Pick a section of hose, especially a low spot where liquid can sit. Wipe it clean first. Then soak a clean cotton rag in hot (not scalding) water, wring it out, and wrap or rub it on the hose for a minute or two. Drop the rag in a zipper bag, seal it, carry it out into fresh air on deck, then open the bag and sniff.

• Rag smells of sewage: that hose is permeated. Washing or wrapping it will not fix it; it needs replacing.
• Rag smells clean: that section is fine. Test every run (toilet to tank, tank to deck fitting, tank to macerator or overboard, and the vent line) before you decide.

If you are not sure, scrub the hose, wait a few days and test again. If the smell returns on a clean hose, it is coming through the wall.

Look at every joint with a flashlight and mirror: stains, crust, damp spots or drips around clamps mean a leak, not permeation. A crooked clamp or a scratched hose barb can leak even when the clamp is tight. Also check:

• The vent line and its hull fitting: a blocked vent makes the system smell worse. Mud daubers love to nest in vent fittings.
• The tank itself: smell near the tank but clean rags on the hoses points to the tank, its fittings or a cracked deck pump-out line.
• The toilet intake: a rotten-egg whiff only when you flush usually comes from sea water sitting in the intake line, not from the waste hoses.
• Slow flushing or a toilet that gets harder to pump: often scale, not smell. Urine and sea water leave hard calcium deposits inside the discharge hose. Raritan warns that, over the years, this buildup can shrink the opening of a waste hose to a fraction of its size and end in a full clog. Squeeze the hose: if it feels rock-hard and the inside is crusted where you can see it, scale is part of your problem.

Trace each hose from end to end and label it with masking tape (for example "toilet to Y-valve", "tank to deck", "vent"). For each run write down:

• The inside diameter printed on the old hose or on the fitting (common sizes are 1 inch and 1-1/2 inch for waste lines and 5/8 inch for vents, but measure yours).
• The length, plus a foot or two extra for each run.
• Where it passes through bulkheads or lockers, and where it has to bend.
• Which fittings are plastic. Old plastic fittings can crack when you pull a hose off, so it is smart to have spares on hand.

Take photos of every connection and every clamp before you touch anything.

Buy hose sold specifically as sanitation hose. Hose for fuel, coolant, exhaust or drinking water is made from different materials and will not hold back odors.

• Premium sanitation hose from the major marine brands is made from odor-resistant rubbers (such as EPDM or butyl), polyurethane blends or special low-plasticizer PVC. In Practical Sailor's long-term test with real sewage, the premium hoses showed no permeation after 30 months.
• Basic white PVC sanitation hose is cheaper and widely sold in small sizes, but Practical Sailor saw possible permeation by 30 months and does not recommend it for waste lines.
• Never use clear vinyl hose for waste or vent lines: it turns yellow and starts to stink quickly.
• Vent lines need sanitation-grade hose too. BoatUS specifically says to include the tank vent hose when you replace.
• Some premium hoses are very stiff and hard to bend in tight spaces; others are soft and easy to fit. Read the maker's bend radius and pick what will fit your boat. Some flexible premium hoses are sold to slide onto standard barbs without heating; follow that hose maker's own fitting instructions.
• Look at the warranty: some premium hoses carry a long written warranty against odor permeation (Raritan offers 10 years on its butyl-rubber SaniFlex). Keep the receipt and the hose markings in your records.
• Any hose that connects to a through-hull must be strong, reinforced hose. A cheap hose there can sink the boat.

Good routing is what keeps new hose from smelling in a few years:

• Keep runs as short and straight as possible.
• After the first rise out of the toilet, slope hoses down toward the holding tank. Any hose will eventually permeate if sewage stands in it.
• The deck pump-out hose should drain back into the tank, with no loops or sags.
• Avoid sharp bends. Hose makers say it is better to use a rigid PVC elbow than to force a kink.
• For long runs, a well-supported Schedule 40 PVC pipe (not thin-wall DWV drain pipe) does not permeate at all.
• Keep any vented (anti-siphon) loop that was installed in the toilet discharge line, at the same height. It stops sea water from siphoning back into the boat. If you are not sure why a loop is there, leave it in place and ask a pro.

1. Pump out the holding tank and flush plenty of fresh water through the toilet into the tank, then pump out again. BoatUS's rule of thumb for clearing a discharge hose is about two pump strokes per foot of hose.
2. Close all head seacocks (intake, discharge or macerator overboard) and tag them "CLOSED, hose off".
3. Turn off power to any electric toilet or macerator at the breaker.
4. Open hatches and run a fan. Put on gloves, glasses and old clothes.
5. Lay out trash bags, rags and a bucket under each joint.

Loosen or cut the clamps. Old sanitation hose is often stuck tight. Cut the hose lengthwise near the fitting with a utility knife, angling the blade away from the barb, and peel it off. Do not pry hard on plastic fittings or the toilet base. As each piece comes out, tape the ends shut or stuff them in a bag right away to keep spills and smell under control.

Scrape any scale off the barbs and wipe them clean. Check for cracks, scored barbs, worn threads and corrosion. Replace any cracked plastic fitting, and any metal fitting that is badly corroded. Look closely at the seacocks while the hoses are off; if one is stiff, cracked or weeps, see the seacock guide before going further.

Cut each piece a few inches longer than you think you need: hose usually gets destroyed when it comes off later, so a little extra length makes future repairs easier.

• Soften stiff hose ends in hot water from a kettle or thermos until they are warm and flexible. Avoid heat guns or open flames; hose makers warn that overheating weakens the hose.
• Use a lubricant the hose maker approves. EPDM hose does not like petroleum products, so water-based or glycol-based lubes are usually safer than grease or oil.
• Push the hose all the way onto the barb. Do not seal joints with silicone or other caulk; it is a short-term fix that hides a bad fit.

• Use all-stainless clamps. Cheap clamps with plated screws rust quickly in a head compartment.
• Double-clamp connections below the waterline, but only if the barb is long enough for both clamps to sit fully on it. A second clamp hanging off the end of the barb just cuts the hose.
• Turn the clamp screws so you can reach them later.
• Tighten firmly but do not crush or cut the hose.
• Support long runs with straps or clamps so the hose cannot sag into new low spots or chafe on sharp edges.

Run the new vent hose with a steady rise to the hull fitting and no dips where water can collect. Clean the vent fitting's small screen: insects, salt and corrosion often block it. An activated-carbon vent filter cuts the smell that comes out of the vent, especially if the vent sits near a hatch or the cockpit. Filters wear out and need replacing; follow the maker's schedule.

Open the seacocks one at a time and check each connection. Flush the toilet several times with clean water and look at every joint with a flashlight. Check again after a day of use and after a week; new hose can settle on the barbs, so snug the clamps if needed. Repeat the hot-rag test in a few weeks as a baseline.

Drain the old pieces into the toilet or holding tank before you pump out, tape or bag the ends, and double-bag everything. Most marinas let you put sealed bags in the regular trash, but ask first and follow local rules. Clean any spills with a disinfectant cleaner that is safe for your hoses and tank (not bleach), then wash your tools.