The Big Toilet Debate!
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Mon Feb 23, 2015 at 10:15am

This article is designed to explain the different options of sanitation available for your narrowboat and should help you decide which system is right for you.

Due to the nature of boats, human waste has to be stored on board, full stop. Each system has a form of tank where the waste is stored and then chemically treated before disposal. It is the method of storage and disposal that is different.

Whatever system you chose you need to responsibly get rid of the waste. Gone are the days of chucking your waste into the canal. I’m sure you will agree that this is for the best!  There are many sanitary stations on the waterway system which are free for you to use at your convenience.

There are basically 3 types of toilets that can be installed on a narrow boat, well 4 if you choose the ‘bucket and chuck it’ option which is no more than a bucket stored under your bed like the old fashioned chamber pots! In today’s modern world it’s highly unlikely a chamber pot is going to be a desirable choice, so let’s look at the other 3 possibilities.

Note - Choice is restricted only by your budget and requirements.

The cassette toilet AKA Porta Potti*

*A Porta Potti is a trade name of a particular make of chemical toilet, but it is often used as a generic term.

There are 3 versions of the cassette toilet; free standing, fitted and remote with vacuum flush. Prices start from around £70.00 but if you have a pressure controlled pump then you will be looking at around £350.00.

The fact that the cassette toilet is free to empty and is easy to maintain makes it a popular choice with many boaters. One down side that applies to all 3 versions is emptying the cassette.

The base of the toilet is a cassette container which collects the waste and is removed from the unit when it needs to be emptied. By keeping an eye on the cassette level you will know when it’s time to empty it.

Another problem you may incur if you are miles away from a sanitary station and the cassette needs emptying you will not be able to do this until you reach the next one. However, to get around this, have a second / third cassette for these occasions.

Cassette Free-standing   


  • Simple.
  • No Charge to empty – there are many sanitation points on the water ways system
  • Easy to empty and a relatively clean job
  • You can carry a spare cassette and empty the full one at your convenience.


  • A full cassette may be heavy for you to carry.
  • Air displaced from the tank when the waste drops in may cause a smell
  • The rinse water tank has to be filled up
  • Doesn’t look very attractive
  • The seat level may be lower than a normal toilet.
  • Has a plastic bowl.

Cassette Fitted


  • Same as the free-standing cassette
  • looks more like a household toilet
  • The seat level is at a good height
  • Unit is very stable.
  • The rinse water maybe part of the boat plumbing.      


  • A full cassette may be heavy for you to carry.
  • Air displaced from the tank when the waste drops in may cause a smell
  • Plastic bowl.

Remote Cassette with vacuum flush  

With the remote cassette version the toilets contents are flushed through pipework to a cassette located elsewhere in the boat.


  • No back smells
  • Ceramic bowl
  • No cost to empty
  • Easy to empty and a relatively clean job
  • If you have a spare cassette, you can empty the full one at your convenience.
  • The rinse water is part of the boat plumbing.   


  • Complex machinery - very sensitive easily blocked.
  • Cassette size 14L
  • A full cassette may be heavy for you to carry.    

The pump out toilet

Pump out toilets look like home from home toilets. They have a ceramic bowl and this is one reason why they are so popular, along with the fact that you do not manually have to empty the tank, the contents are pumped out via pipe work at a pump out station.

Pump out stations can be found at boat yards, marinas and sometimes along the canal network. There is a charge for using this service and costs will vary from station to station, you will be looking at paying somewhere from £15.00 - £20.00 approx.

You can if you wanted to (but not sure why you would) buy a pump out kit and dispose of the waste when you get to the sanitation stations. If you decided to do the pump out with a kit you may as well be using a cassette toilet.  There are a wide range of sophisticated pump out toilets available to buy with electric flushes, macerator units, and remote tanks. Warning - a number of sanitary stations now have notices prohibiting this practice.

In case of emergency; such as if the pump out tank is full and you are not near a pump out station, consider also carrying a cassette toilet on board, to have another option until the tank is emptied.

One other thing to consider with the pump out toilet is carrying the waste around with you in between emptying, some people find this off putting and so prefer the cassette toilet which they can empty more regularly.  

There are 2 different types of pumpout toilets, the” dump through” and the vacuum air toilet / compressed air toilet.

Pump out Dump Through

This is where the toilet is directly over the waste tank; the waste goes straight into the large tank underneath. The seals do gradually deteriorate, which leads to smells escaping from the tank. Replacing the seals as you can imagine is not a pleasant task.

These toilets are in the region of £800.

The Vacuum / Compressed Air Toilets

These are very desirable as they seal off the waste once the toilet has been flushed with a flap. But with this convenience comes the high price tag, a vacuum toilet will be around £1000 and an air compressed loo will be at least £2000!

The compost toilet “The Eco Toilet”

This toilet is the newest option for use on boats, however it has been used on land for some time. There are a number of companies now selling these toilets, simply look online and you will be able to view many options.

Prices would be around £800 up to £1800 depending on the model. It has been said they only need to be emptied once a year! Depending on the usage will depend on how often you need to empty the unit, but you are looking at every few months to a year rather than every week. It is very eco-friendly as it doesn’t use hazardous or environmentally damaging chemicals and produces excellent compost. Some of the models actually separate the urine from the solids, so you can responsibly disposed of the urine and then the solid matter is composted in the other unit.

Round Up On Toilets

  • Make sure you take the time to read the toilets instructions to understand how the system works and how to maintain it.
  • Pump out toilets you carry your waste around with you; cassette toilets can be emptied daily.
  • Pumping out waste is chargeable, whereas cassette waste is free to dispose of.
  • The Cassette toilet system is the cheapest solution
  • The composting toilet is the most eco friendly
  • Holding tank systems can produce bad smells if not looked after
  • Cassette toilets require regular emptying   
  • Pump-out toilet bowls look most like a domestic loo