Choosing the best type of toilet for a narrowboat

There are two types of toilet you can use on your narrowboat; there’s the pump out toilet and the cassette toilet (sometimes referred to as a “Porta Potti). Each has advantages and disadvantages but which is best for you?

Porta Potti Elegance Narrowboat Toilet

Porta Potti Elegance Narrowboat Toilet

The Narrowboat Cassette Toilet

The cheapest to buy and maintain is the cassette toilet. It’s basically a toilet seat on a frame secured over a detatchable waste tank. They are compact and reasonably pleasing to the eye. The toilet pictured is the model that I have on my own boat. I inherited one when I bought the boat. I liked the design, capacity and ease of use but I didn’t like the fact that it had been used by someone else so I replaced it with the same model.

This particular model has a 15l flush tank, a 21l waste tank and is roughly cube shaped and 400mm on each side. There are cassette toilets that you can plumb into your boat’s water supply for the flush water but this one has a self contained manual flush.

The advantage of using a cassette toilet is that you don’t have to move your boat to a service point in order to empty your toilet. This needs to be a consideration if you intend to spend much time on your boat over the colder winter months. This winter (2011/2012) has been very mild to date but last year the whole canal system was frozen for six weeks so boats with pump out toilets only had a bit of a problem. There is also the cost element. You can usually empty your cassette free of charge.

The disadvantages of cassette toilets on narrowboats are:

  • The weight of the waste cassette: My water tank holds 21l so, when the tank is full it weighs roughly the same as a bag of coal. maneuvering a full cassette around the narrow confines of a narrowboat trying to avoid touching curtains and seat covers is hard work.
  • Capacity: If there are two or more of you on board you will probably need to empty your cassette at least every other day. It’s a bit of a pain
  • Flushing: The manual flush of most cassette toilets is a bit of a weak affair. In fact, if you don’t mind me being quite candid here, I tend to just use my toilet for having a wee. Flushing anything else along with wads of paper is a bit unpleasant.

The narrowboat pump out toilet

It looks and acts just like a normal toilet. At least the better ones do. All of them have a plastic or stainless steel waste tank very close to the toilet. The tank is often stored in the space under your bed (so when you’re laying in bed on a windy night being rocked to sleep by what you think are waves outside the boat… maybe it’s not waves you hear). Many of the basic pump out toilets simply have a flap at the bottom of the bowl which, when opened, allows the waste to drop straight into the tank. The good thing about this design is that it’s a very simple setup so there’s very little to go wrong. The bad thing is that you can see into the tank and its contents every time you flush the toilet. Handy for checking when the tank is almost full, but not very pleasant.

The more sophisticated toilets may have electric pre flush and post flush plus a macerator for chopping up your unmentionables (which can sometimes get clogged up with dried out toilet paper).

Because pump out toilets have a large waste tank they don’t need emptying so often. A family of four eating and drinking on board all the time though will probably have to empty the tank once a week at a cost of about ?15.

The disadvantages of a pump out toilet are:

  1. You have to take your boat to a service point so if you can’t move your boat because of bad weather and/or canal or lock restrictions you have a problem
  2. The cost: Anywhere between ?10 and ?20 each time you want to empty your tank
  3. Potential for problems: The cassette toilet is a very simple affair with few mechanical parts. The basic ones rarely go wrong. The more high-tech your toilet, the greater the risk.

Whichever toilet you choose, you’ll get much closer to the contents of your toilet than you ever do at home, but you’ll soon get used to it.

Useful Information
Paul Smith

After six and a half years living on a narrowboat on England's inland waterways, Paul and his wife Cynthia wandered Europe by motorhome during the winter, and on the Dutch and French waterways in the warmer months on their 35' Dutch motor cruiser. However, the pull of England's muddy ditches proved too much for them. Now they're back where they belong, constantly stuck in mud in a beautiful traditional narrowboat.

Click Here to Leave a Comment Below 21 comments
Pengalanty - Wednesday,1 February, 2012

Actually there are THREE types of toilet usually associated with narrowboats >>
Bucket and Chuck it types (Porta Potties, Cassettes etc)
Holding tanks (Vacu-Flush,Dump Through, Masserator etc)
Composting Toilets (Envirolet and many others)

Regarding the composting types,they are not generally very popular and are
specialist types, for the people who insist on being green and “OddBods” like

I didn’t get on with my “Envirolet” (MyComposting Loo) for more than
18-months or so, until I studied the mechanics of it

I then did a modification. Now, I wouldn’t have any other type of loo. It works
fine and is less work than the other two types

I wouldn’t have the *bucket and chuck it* types because one must always look
around for sani-stations and basically cruise from one sani-station to another
every 3 days or so

I wouldn’t have the *pump-out* type as this is a continual drain on funds paying
for pump-outs every 4 – 6 weeks (Usually £10 – £18 per pump out – even more
on the Southern canals!)

With my Composting loo, I spend about an hour every 3 – 4 months, emptying
the dry friable waste compost from the under tray. and it costs me nothing.
That is not exactly true – I do buy liquid compost accelerator from the Garden
centres and I use “Bio-Magic” occasionally in the very hot weather, (Summer),
to keep it “sweet”

If it is looked after, there is no unpleasant odour, as some people suggest. Only
composting loos that are *not* looked after properly get pongy! (Anaerobic
decomposition) which is to be avoided

One can usually tell when a boat is fitted with a *Composter*, because they have
a roof vent with a revolving anti-downdraught cowl

Because most of these types of loo have a small extractor fan in the vent system,
there isn’t a problem when one has a *Curry Night Out* There is never an odour
in the loo, as this is immediately drawn out through the loo and discharged out
the roof vent – Sheer bliss for the crew!

There we are, getting on to the most popular of boaters subjects – loos! And what
type have YOU got?


    alan - Sunday,29 June, 2014

    I’m currently doing loads of research on everything related to living afloat before I take the plunge and always thought that a composting toilet was the way forward. Interesting reading your comments, the modification you mention is it something a competent DIYer could do. Thanks in advance. Alan


      Paul Smith - Sunday,29 June, 2014

      Hi Alan (Dickins),
      This comment system isn’t used much these days. If you want an answer on composting toilets, you’re far more likely to get a response if you post your question on the forum.


admin - Thursday,2 February, 2012

I stand corected Allan. I should have included the composting toilet option. For anyone interested in composting toilets, you can find out more about Allan’s Envirolet here


Pengalanty - Thursday,2 February, 2012

Please note that I would not recommend the “Envirolet” toilet today. The exchange rate
makes it too expensive in the UK. It is not suitable in the UK environment, because our
per cent relative humidity is high, always being in the 65% to 100% humidity range
(The UK Being surrounded by water)

The Envirolet” is designed for the Canadian and USA climate, which may surprise you
but the relative humidity over there is “Arid” at around 3%

I modified my loo to separate the solids from the liquid and treat the solids (Squirt
a prepared liquid over the mass) on each use. I also add a small amount of earth/peat
compost mix and sometimes diluted Bio-magic. (I mention this for those who are
interested). It is simple and quick, taking the same time as flushing a loo (Pump-out type)

I would recommend a composter that separates the fluid and solids. There are a few like
this on the market today and they are all less expensive than the Envirolet and need no
modification. The only work installing them is to fit a vent, preferably vertical, rather
than through the side of the boat, (More efficient)


    midsummer.night.dream - Friday,17 February, 2012

    can you tell me what envirolet you have and what the modifications were


Swilks - Monday,6 February, 2012

Firstly, I would like to say thanks for the info on your website. My husband and I are doing our research now and have a two year plan before we intent to live a board a narrow boat. We have really found your site useful. I also have a question in relation to on board toilets. We are familiar with the cassette toilet as we have a caravan but wonder where they are emptied when you are not in a marina. They are often quoted as a solution for when it’s impossible to empty the pump out options? Also with regards the compost type toilet, how is the final product disposed of? Sorry if they seem stupid questions, I’m just trying to determine the finer details…..or in this case not so ‘fine’.


    admin - Monday,6 February, 2012

    Where can you empty a cassette? At every marina, some boatyards and at some BW service points. The cassette emptying points are called “Elsan” points. A couple of things you need to bear in mind with cassette toilets; (1) the cassettes are heavy to manouver through the boat and to wherever you are going to empty it and (2) during a cold spell the water used for rinsing your cassette at the Elsan point may be frozen. I will ask Allan to answer your question about compost.


    Pengalanty - Monday,6 February, 2012

    Thank you for your questions – And NO! – They are not stupid or simple ones and anyone not having previous experience is likely to ask similar questions, so let us be positive in the reply for you to enable you to make, “What will be a VERY IMPORTANT decision”, as toilet maintenance does affect your routine lifestyle

    Where are Pump-outs emptied?

    All around the canal system (And less so on the rivers) there are “Sani-Stations”. They are mostly operated by marinas around the system and is a paid service. The cost of a pump-out varies. It’s between £10 -£20. (In the south, I have heard of the fee being as much as £25! – around Evesham, I think). Generally speaking, the further north you are, the more reasonable the charge

    British Waterways, (Soon to become a trust) also have pump-out stations in strategic places. There are operated by a card system, similar to a credit card that is “pre-loaded” and one pays with this. I might be wrong on this score and it is possible that it is a coin system and ones buys coins along the way- Perhaps someone else “Who Knows” will comment?

    One is also able to purchase self-pump-out kits (Manual and Electric). Prices and purchase available from: LeeSan, at Fenny Compton. Warickshire – Contact details , as follows:
    Telephone: +44 (0)1295 770000 Fax: +44 (0)1295 770022 e-mail: sales@leesan.com

    As a guide,(For two of you living on a boat full time), pump-out frequencies are normally around a 4 week period. (This may depend on how much beer, wine and water you drink and how often one uses pub/restaurant toilets too! Remember, effluent is 90% fluid and 10% solids – need I say more?

    Sani- stations are marked on the special canal maps, produced by Nicholsons and other Printers; just pop into any chandlery shop and you should be able to get one off the shelf for the area(s) you are interested in. Smiths and Watermans should also have them

    Cassette toilets can usually be emptied and washed out (Hose) by many water points but not all. This is also marked on the maps

    With regards to composting toilets, the friable waste, collected from the lower tray, (Should be friable and clean), rather like 3/8″ to dust scalpings and can be handled – I only mention this because it is not unpleasant, as one would imagine.

    In my case, I put this in a bucket, with a lid on and place it on the roof for another period of time as the process is not fully completed, (That’s by the by and is the method I use). When I pass through woods, or ploughed land, hedges or “natural” growth, the composted material can be broadcast. Note: When you pass stinging nettles about 10’0″ high, I have probably cruised by some time earlier and may be responsible for the growth!

    I wish you good luck with the choice of your proposed new narrowboat – I am confident you will wish you had taken this decision years ago! Warm regards, ~Allan~


      Swilks - Wednesday,11 April, 2012

      Allan, thanks very much for the comprehensive reply. We love reading the site and it’s keeping our enthusiasm well and truly topped up.


lyraboat - Tuesday,7 February, 2012

When we set out to fitout our boat, nearly 7 years ago now, my wife wanted a ceramic bowl toilet. At that time all the cassette units we could see used plastic bowls. Then we found the Vacuflush. this boasted a remote cassette and ceramic bowl. We jumped at it.
So far it hasn’t been too bad. the cassett lasts 4 person/days, so with guests on board I have to empty it every day, otherwise it last two days. The down sides of this unit are: It’s noisy while drawing a vacuum. You have to buy and fit new seals to the toilet bowl and the cassette mounting occasionally. More importantly, it no longer holds its vacuum so I’ve installed a switch next to the loo and turn it on when you need to flush it and off again afterwards. This works well.
So, summing it up, it works well for us but it isn’t perfect.


    mike - Monday,12 March, 2012

    Dear Lyraboat,
    We purchased a second hand boat last year and are now haveing problems with our Dometic vacuflush toilet. It sounds like yours may be similar and I have heard you can no longer get spare parts. Ours leaks when you flush it. Do you have any advice.
    many thanks.


enkiboat - Sunday,19 February, 2012

When we bought our last boat we wanted a ceramic affair that looked like a toilet but – after spending weekends cracking ice and doing a pile of locks in the snow to pump out – we gave up and bought a portapotti. Even when extended cruising, we never used the pumpout at all for the next 8 years. They’re cheap, don’t infuse the boat with a musky odour and last for years too.


pitstop - Saturday,17 March, 2012

We bought our ex hire boat 3years ago and have found our macerator/pump out system very effective. With a conventional flush system it has the ‘feel’ of a conventional loo but we do not seem ot suffer from the problem of having to empty it as often as we had expected. The boat has twin holding tanks, one under each of two single berths and we seeem t0 be able to go for 6 – 8 weeks between pump outs. Another boat of the same type on our marina claim to be able to go for 8 – 10weeks between pump outs. On that basis at £10 for a pump out, the cost is around 50p per person per week which seems very reasonable for the convenience of not having to carry a portapotti waste to the sanitary station every few days! The composter does sound interesting but I think I would be worried about what might happen if anything went wrong with the composting action at any time! I suppose you could always have a portapotty in the cupboard just in case just as we do now. Given the choice, if we found ourselves in the position of being able to buy another boat, I think we would still probably choose the macerator/pump out system again – its the convenience.


chraine - Friday,6 April, 2012

Have just joined this site and thank you Paul for bringing folk together – even over such a topic as ‘loos’ We are in the process of building and fitting out a boat. One thing that we would appreciate is comments on the ease of disposal of a port poti down a domestic loo? Whilst there is a cost to pump out how many BW sites are there for a sluice ? I understand that Paul is developing a marina map but apart from guide books having ‘facilities’ on the map would be of interest.


    admin - Friday,6 April, 2012

    Hello and welcome to the site. Please DO NOT think about emptying a cassette down a toilet. It makes an awful mess! You need to empty your cassette in what is referred to as an “Elsan” disposal point. These are like an open drain specifically for toilet waste and usually with a water supply nearby to wash down the drain and your cassette once it is empty. You will find Elsan points at marinas, boatyards and at British Waterways service points along the canal.


Swilks - Wednesday,11 April, 2012

Only just got back on the site so a belated thanks for the replies. They are very useful.


Dannyboy1 - Sunday,15 April, 2012

New to this, so excuse any ignorance… In fitting out a liveaboard, is there a ‘middle route’ of porta potti AND holding tank(s)? Thus, the mechanical simplicity of the porta potti and the convenience of larger storage when not close to sanitation points? Or is there a restriction on what can be pumped out (chemical etc.)?


    admin - Sunday,15 April, 2012

    A pump out toilet has a holding tank large enough for a number of weeks (depending upon the number of people using it and the frequency of use). The basic “pump out” toilet is mechanically as simple as a cassette toilet. It is referred to as a “dump through” toilet. Flushing it involves opening a flap which drops the waste into the holding tank beneath. The cassette toilet, of which Porta Potti is a make, works on the same principle. The middle ground, if there is one, is to have a cassette toilet with one or more spare cassettes in case you are caught short.


powerslide - Thursday,26 April, 2012

In response to Dannyboyz question, I’m just looking to buy a 70ft boat which was originally an 8-berth. It has had 2 pump out toilets removed and replaced by a single cassette type (with spare cassette) since it was being lived on by a single person. I also want to live on board but in addition, I plan to take youth groups away on holiday with it so I am planning to add another pair of bunks (making 10 altogether) and re-instate at least one of the pumpout loos. The cassette would be enough for me on my own but not practical for a larger group. Thus at least one pump out toilet will be needed. I may even need to re-instate both pumpouts (the holding tanks are still in place) but either way, I would still keep the cassette toilet as back-up. You can empty a cassette down a foul manhole (NOT a stormwater drain) or in desperation dig a hole and bury it somewhere discretely in the countryside if you cannot get to a disposal point.


tramman - Sunday,2 March, 2014

do not know any of these i had a bucket on the joey and used the manhole closet the boat at the time ah happy days



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