How To Unblock A Toilet On A Boat | Page 3 Of 4 | Become A Cruiser
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How To Unblock a Toilet On a Boat

How To Unblock a Blocked Sanitary Hose

Difficulty Factor: 2-4 Beer Reward
Disgusting Scale: 5-9

Screen Shot 2020 11 30 at 07.43.58 2 How To Unblock a Toilet On a Boat
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Total Time Needed :



Required Tools:

– Screwdriver
– Flexible Socket Driver
– Wrench
– Stanley Knife

Things Needed?

– Pair of good quality latex gloves
– Clean up rags and disinfectant

If the bowl and pump/ macerator are not blocked your task just unfortunately just got a little more difficult and time-consuming.

On average you should need about an hour for this mission. If you have long complex hose runs with heavily scaled hoses you may be in for a full day of work. Pipes without scale are far easier to remove and reinstall.

Before You Start


Don’t be tempted to try a chemical solution. That includes Muriatic acid. You will only make your life more difficult down the line.

Make sure to clear a path from where you will remove to hose all the way to where you will work on the hose. Remember you may be dripping biohazardous water contaminated with sewage as you move to where you will work with the hose outside of the boat. Be sure there are no carpets, cushions, etc. that cannot be disinfected in or near your path.

Step 1

Open all access covers and panels to give you access to the length of the pipe

Completely undo all hose clamps from both sides of the pipe. Push the clamps off of the barb and down the pipe to make sure there is no added resistance.

Pry off the hose from the barb on both ends. Try carefully to pry off with a screwdriver or pick. Be careful they tend to slip off of the rounded barbs. If the hose is stubborn and will not come off try a little hot air but be careful not to damage any surrounding structures.

If you will be replacing the hose or have about a foot of extra hose simply use a Stanley knife and cut the hose lengthways down the barb. Making sure not to damage the barb. Where possible I always make sure I have an extra 1.5 to 2ft of spare hose on any section of the sanitary system I think I may have to remove. Cutting off a section of the hose can be far easier than fighting for hours in a small space with a sanitary hose that will not come off of a barb.

Next work section by section, foot by foot to feed the hose out. With a heavily scaled sanitary hose, it is easier to move a section and then incrementally move the pipe along. Then trying to wrestle and pull the pipe from the end in one movement.

Step 2

See Step 3 if you will be replacing the hose.

If you will be reusing the hose. Take the hose to the back transom or someplace where you can stand and work with a good source of water. I find using the hydraulic action of seawater best.

Start at one end and bang the hose firmly and repeatedly on a hard part of the boat (or dock or even take the hose on an outing to the beach) that will not be damaged. Work down the hose little by little. Then depending on the hose length fill with water and rapidly pump the hose up and down or across the water (making sure that one end remains submerged). This hydraulic action will start to free the blockage and accumulated scale. Repeat until the pipe is unblocked and free of scale.

If you cannot unblock the hose try push a fairly rigid hose with a smaller diameter up the blocked hose to break up the blockage. You might need to alternate with banging the hose and pushing another hose through the blocked sanitary hose to clear the blockage.

Step 3

Ensure the ends of the hose are cut neatly at a ninety-degree angle. Remove any residual plastic burs. Reinstall. If the hose is stubborn to go on lubricate the inside with a little dish soap. Ensure that the hose is properly clamped at all joints. Reopen the seacock and inspect for leaks.

If the sanitary hose which was removed was heavily calcified, increase the quantity of water that is pushed through the pipe with each flushing. And consider increasing the frequency of muriatic acid flushing treatments.

I struggled, cursed, and swore every time I had to take off clamps on our sanitary, plumbing, even fuel systems. As so often you cannot get a tool into the space required to adjust a clamp’s tension.

Then a buddy of mine introduced me to a flexible socket driver for clamps. Oh, the joy! I have saved so much skin from been ripped off my knuckles they are worth every penny.

This Article Continues over Multiple Pages – Please Click on Page 4 Below

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Hi, I’m Nic! Our Family of four have been out cruising since 2016. We have sailed about 15,000nm, almost halfway around the world. We sold everything, took the leap of faith, and bought a 10-year-old Lagoon 380 ex-charter catamaran. We’ve fixed every system on the boat, often more than once. Cruising has been such a wonderful, positive experience for our family that I want to share my tips to help you Become a Cruiser.

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