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    


Paul Stevens | Thu Nov 26, 2015 at 10:01pm
I'm seriously thinking of purchasing a Eco Toilet for my narrow boat and have been on the internet looking at all the options but feel confused with all the different specs available
Horatio Nelson-Burke | Sat Jan 2, 2016 at 4:08pm
Very interesting post. I've just bought a large canal boat and the only thing that I've been dreading is sorting out and maintaining the WC facilities I've a cassette loo installed but I'll be of to the boat show next week and I'll probably buy an Eco toilet, It looks like it will save an awful lot of work in the long run
Whilton Marina | Mon Jan 4, 2016 at 2:24pm
Hello Paul, you are probably best to talk to a specialist about composting toilets, or join one of the many Canal Forums to get other peoples opinions.
Sue Lees | Tue Mar 1, 2016 at 5:57pm
There's a great group FB 'Compost Toilets for Boats and Off Grid Living'. Lots of us have either bought or got diy compost toilets and we can definitely vouch for them.
Geoff Herbert | Wed Mar 16, 2016 at 6:56am
How much space needed for the compost WC
Whilton Marina | Wed Mar 23, 2016 at 12:40pm
Hello Geoff, Composting toilets take up the same amount of space on a boat as other toilets. However it's best to talk to a specialist about composting toilets.
Mick | Wed Jun 15, 2016 at 6:24pm
Can you get a drop through toilet with a built in macerator that sits directly on top of the tank.
Whilton Marina | Wed Jun 22, 2016 at 11:21am
Hello Mick, it is possible to put a macerator toilet on a narrowboat with a holding tank, it would be best to speak to a company such as Saniflo who supply macerator toilets to discuss the options available.
Bob Terry | Sun Jun 26, 2016 at 7:09pm
We have a drop through pump out toilet on our Narrow boat which works very well but produces extremely foul smells when operated. We tend to operate the flush as quickly as possible to minimise the time the tank is open to the bathroom. This helps but is not a solution. How can we minimise the smells. Or are there any additives we can add to the tank to help. We have tried large bottles of chemicals as used in cassette loo''s but it seems due to size we would need to add it by the gallon. Not particularly cost effective. Any suggestions. Bob Terry
Whilton Marina | Mon Jun 27, 2016 at 3:57pm
Hello Bob, best way of getting rid of the residual solids, which smell is to make sure that you flush plenty of water through the tank during the pump out. Try this;trap a hose under the flap at bottom of toilet (not drinking water hose) turn tap on while the waste being removed from tank, rock the boat gently all the time, if you look through the pump out hose’s sight glass you’ll see how much muck is dislodged initially. Keep doing this until the liquid is runs clear through the sight glass, only works with a dump through toilet not a macerator. For macerator toilet, pump all waste out of the tank, take the pump out hose off the outlet and squirt a few gallons of water back into the tank through the outlet, pump the liquid out again, repeat until liquid comes out clear. Try using toilet fluid which uses bacteria rather than chemicals to neutralise the smell. but, if whoever cleans the toilets in the past used a chemical like bleach, the bacteria is destroyed & this will not work.
Peter Boreham | Sat Sep 10, 2016 at 5:47pm
I have had my narrowboat in The Netherlands this summer, the pump out ( Dump through) toilet has been no problem here. . The highest price I have paid for a pump-out is 2 Euros, most machines seem to be priced at 1 Euro for 3 minutes of pump out. Many towns provide FREE pump out for boats on their moorings. So why is it so expensive to pump out your toilet in RIP-OFF BRITAIN? Perhaps the Environment Agency could answer this.
Whilton Marina | Tue Sep 20, 2016 at 1:36pm
Hello Peter, We can only assume that in The Netherlands the pump out facilities on the waterways there are owned by the state, or are subsidised in some way. In the UK pumpout facilities are generally owned and run by marinas who have to maintain and empty them, and there is obviously cost involved in getting them emptied.
mark Robertson | Wed Sep 21, 2016 at 7:43am
We have a macerator toilet which pumps into a holding tank..Would a Jabsco Twist N Lock regular manual Toilet be a good replacement as I do not like the idea that a small one way valve seems to be the only thing stopping the water supply to our existing toilet from flooding the boat and for peace of mind want to install a toilet without electricity and with a manual turn on/off for water.
Whilton Marina | Mon Sep 26, 2016 at 4:21pm
Hello MarkBest to speak to a supplier of the Jabsco Twist & Lock toilet to get advice on this. Or any good Chandlery should be able to advise you on a suitable alternative to the macerator toilet.
Mark Taylor | Sat Oct 29, 2016 at 4:58am
Over the winter I have decided to use my pump out toilet (rather than the cassette variant over always used in the past) however.... I can't find any sort of sight glass or level indicator ! How can I establish when the time comes to get a pump out done ? Btw it has a "traveller" emblem on a plate at the back of the seat.
Whilton Marina | Tue Nov 1, 2016 at 4:21pm
Hello Mark, You can have fitted a sensor gauge which will indicate when the holding waste tank is full.
C carson | Tue Aug 1, 2017 at 3:42pm
We have a pump out toilet with macerator which has worked perfectly for 3 years. In the last couple of months it has begun to smell. How can we sort this problem out? No bleach has been used.
Whilton Marina | Mon Aug 14, 2017 at 4:35pm
Hello C CarsonWe would advise you to check the seals that may be loose or damaged. It also could possible by a blockage building up. Probably best to speak to the manufacturer of the toilet or try online forums for peoples ideas.
Iza B | Thu Nov 30, 2017 at 1:24pm
Hi, thinking to get a compost toilet fitted to my barge... who can answer the question on where do you get them emptied in and around London?
Whilton Marina | Mon Dec 4, 2017 at 12:04pm
Hi Iza, The whole point of composting toilets is that the waste is broken down into harmless compost which can be used on the garden or disposed of in domestic refuse or recycling systems once it has decomposed enough. In order to ensure that all pathogens or other harmful bacteria are neutralised, the Environment Agency advise that such compost material should be kept on site for 26 weeks. Speak to a supplier of Eco toilets for more information, such as Eco toilets.
John hopkins | Tue Jan 9, 2018 at 3:09pm
I am having a widebeam boat built .can I av a saniflo macerator fitted an normal toilet fitted? If not why?Many thanks
Whilton Marina | Mon Jan 22, 2018 at 4:12pm
Hi John, are you asking if you can have two different toilets fitted?
Mark Meopham | Thu Mar 22, 2018 at 10:26am
We have had Thetford cassette toilet on our Narrowboat but now moving up to a widebeam with a pump out but the boat hasn’t been used in about 4 years. What cleaners / solutions should we use with a pump out?Still Blue & Pink or is there something better?
Gill | Sun Mar 25, 2018 at 11:48am
Any idea of how much it would cost to have a pump out toilet removed, I have seen a boat I want to buy and this is the only thing stopping me.
Whilton Marina | Tue Apr 3, 2018 at 1:37pm
Hello Gill, Toilet treatments come in four basic formulations.Chemical treatments are the most popular because they provide the best odor control. Some include chemicals that kill bacteria, but the best chemical treatments deodorize using chemical reactions with odor-causing molecules. Some contain additives that dissolve waste. They can be added to tanks that contain other treatments without cleaning the tank. Enzyme treatments accelerate the digestion of organic materials in waste and neutralize odors at the same time. Nitrates are environmentally friendly, and are ideal for systems with less ventilation. They speed up the breakdown process and reduce odors. Bio-active treatments contain live aerobic bacteria which break down waste, reproduce and crowd out anaerobic (odor-producing) bacteria, they multiply and continue to work long after treatment is complete. However, the microbes require a well-ventilated and residual free holding tank to survive.
Kate Saffin | Fri Apr 13, 2018 at 4:07pm
A note on free standing cassette loos - Porta Potti and similar. You mention being able to buy space cassettes - I've never been able to find spares for the free standing ones. I think they are geared to camping and short term use. I found the only option was to buy a complete unit, which seemed rather wasteful, and was the start of my journey to composting.
Whilton Marina | Mon Apr 16, 2018 at 11:16am
Hello Kate,Thank you for sharing your experience with us.
Bill Stan | Wed Jan 23, 2019 at 3:58pm
How easy is it to remove a Pump out Dump Through tank? I'd rather have a cassette or composting loo.
Whilton Marina | Mon Feb 25, 2019 at 3:34pm
Hello Bill, If the pump out toilet tank is integral you will have to leave it in situ and seal the tank off before fitting a cassette or composting toilet. Also some tanks are very large and cumbersome and may have to be cut apart in order to remove from the boat.
Donna yates | Tue Apr 14, 2020 at 11:13am
Do you have to use special bleach and washing up liquid and toilet roll etc on a boat?
Whilton Marina | Tue Apr 28, 2020 at 2:09pm
Hello Donna, Ideally you should us the most environmentally friendly products available in the toilet and for washing up, to enable the products to biodegrade as quickly as possible and be environmentally friendly.
Nick Wild | Sun May 24, 2020 at 1:51pm
Hi I've been looking at different types if wc's for my canal boat, I think I'll be going for a composting toilet, although I've just been reading up on incinerator toilets, is it possible to use those on a canal boat?
Whilton Marina | Mon Jun 1, 2020 at 10:45am
Hello Nick, We haven't come across a narrowboat with an incinerator toilet so unfortunately we don't know much about them. Best to speak to a company who specialises in them for their advice. Such as LeeSan.
Andy Brown | Sun Jun 28, 2020 at 10:56am
Hi, is it possible to replace a cassette toilet with a pump out system?
Whilton Marina | Thu Jul 16, 2020 at 3:19pm
Hi Andy, It is possible to replace a cassette toilet with a pump out toilet, however depending on the boat it could involve major alterations which may be substantially costly.
Whilton Marina | Thu Jul 16, 2020 at 3:21pm
You can replace a cassette toilet with a pump out, cost wise this will be different from boat to boat as it all depends on the boat layout, how big tank do you need, type of toilet fitted and the work entailed in fitting the new system, will they need to modify bulkhead walls etc….. as a rough price you would be looking at £2000.
Ade | Thu Oct 8, 2020 at 3:14pm
I’ve just had the integral waste tank on my boat pumped out but when I ‘dipped it’ with a stick there’s still around three inches in there (clear-ish) . Is it normal for the pump not to remove all the liquid. I only ask as I was thinking of switching to a cassette toilet and not using the waste tank for the foreseeable future.
Whilton Marina | Fri Oct 16, 2020 at 4:16pm
Hi Ade, Pumping out the tank will leave a small amount of liquid in the tank, It is normal practice to add 'Blue' toilet waste cleaner in the tank to stop the liquid solidifying. Many Thanks
Rob Owen | Fri Mar 5, 2021 at 8:02pm
Hi, we're in the process of having our boat built and originally were going for a composite. I have since read that CRT will no longer allow disposing of waste into bins so where does it go?2nd option is for a pumpout but I've read that there's a small smell. Is this with older boats? Thanks for you discussions, they're so useful for novices. :)
Richard | Mon Nov 22, 2021 at 10:38am
Hi, please can you advise what size (capacity) is best for a pump out tank. I've seen some narrowboats with what I think are small holding tanks ie 26 to 50 gallons, would this mean regular pump outs for two people living aboard fulltime? I'm considering getting a cassette toilet just for liquid and saving the pump out for solids to reduce number of pump outs required.
Whilton Marina | Tue Nov 23, 2021 at 9:58am
Hi Rob, Ive found this webpage on the CRT website hopefully this will help you with all your questions. Thanks
Whilton Marina | Tue Nov 23, 2021 at 9:59am
Hi Richard, LeeSan Marina Sanitation will be able to help you with all your questions - https://www.leesan.comThanks

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