Toilets on canal boats

Let us now turn to the most popular subject of discussion amongst canal boaters: the toilet. Being on a boat means dealing with power, water and waste when away from a marina or other facilities and by definition this means your toilet contents have to be stored somehow and emptied later. This is where things get yucky and is one reason boating is not for the squeamish.

There are four main types of toilet system:

  • Cassette
  • Pump-out
  • Composting / separating
  • Incinerating

Of these, the first two are by far and away the most widely used. The third gained popularity when the Canal & River Trust encouraged it but they’ve since rescinded their support, to the ire of any boater who installed such a toilet. The fourth is the holy grail but has some substantial drawbacks.

The cassette system uses a small, portable plastic tank underneath the toilet bowl which can be removed and carried to a dump point where the contents can be tipped away through a spout on the cassette. And by tipped, I do mean you physically lifting the cassette and pointing the spout down the hole.

While some toilets (notably the Thetford models) use a physically separate tank, others such as the Porta Potti have the entire base of the toilet as the tank so separating them requires disconnecting the top and bottom of the unit.

In essence they’re using the same principle though, of a small portable container for the waste which you empty by hand. This type of toilet is also often found in campervans and motorhomes.

A sealed flap on top of the cassette is opened when you want to use the loo and closed afterwards to prevent smells from the cassette pervading the bathroom (in theory).

You are also supposed to add chemicals to the cassette to assist with smells and break down the waste for smoother disposal but that stuff is not cheap and boaters often improvise, with bio laundry liquid supposedly having the same effect at a much lower price and that’s what I used.

Whilst tipping 15-20 litres of your family’s poo and wee into an often somewhat grim metal tube every two or three days may sound like a distinctly unappealing prospect, the cassette toilet is very popular and has some distinct benefits over the other options:-

  • Your capacity is limited only by the number of cassettes you can carry on board (albeit most boats carry just two, one in use and one spare)
  • It’s totally free to dump the waste at any Canal and River Trust “Elsan[1]” point, of which there are many dotted around the system[2].
  • If your boat gets frozen in during winter, you can still take the cassette out and walk or even drive to the nearest dump point, if you happen to have a car.

If you’re still grimacing at that notion, let’s examine the pump-out system. This too involves a tank but one that’s substantially larger than a cassette and is built in to the boat.

The tanks are usually constructed from stainless steel or some form of tough plastic. In its most basic form, called the “drop-through”, the tank is directly underneath the toilet so your waste just drops through a hole into the tank, with a little flap to close once you’ve finished to prevent smells.

A more sophisticated version has the tank remote from the toilet (often, somewhat unglamorously, under the bed so that sloshing noise you hear at night is likely not any little waves on the canal…) and a macerating pump that both chomps up the solids and pushes the waste to the tank.

When the tank is full (they have gauges to let you know), the entire boat must be taken to a pump-out station to be emptied. These are usually found at marinas although there are some on the canalside provided by the CRT[3].

To empty the tank, a suction hose is connected to a socket somewhere on the boat and the waste is sucked up and out by the machine. Water is then squirted down to sluice things out a bit and that too is then sucked out.

Each emptying will cost anywhere from £15 to £35 depending on how extortionate the marina’s pricing is and this will sometimes be based on a certain amount of time for sucking the waste out.

Note that even the CRT pump-outs make a charge (just for pump out; not for cassette disposal). They used to require you to purchase an activation card in advance (a little sliver of cardboard with a magnetic stripe on it, like a train ticket) but it was not uncommon to then hear of these failing to be read properly by the pump-out machines so they’re now updating the facilities to just use a contactless payment card instead.

You can buy pump-out kits which enable you to run a hose from your tank over to an Elsan point (which are usually used for emptying cassettes) and therefore it would be free to use – but I’ve never heard anyone say anything good about these kits. They seem to be a bit of a hassle.

Pump-outs have these benefits:

  • Much larger capacity than a single cassette so depending on your tank’s size you could go for a few weeks between pump-outs instead of frantically boating to the nearest Elsan point every few days.
  • They use traditional flush toilets so they feel more “home like”

As already noted however, pump-outs cost money even at the CRT facilities. Worse – far worse – it is certainly not unheard of for the boat’s macerating pump to get jammed, especially if guests put things down the loo that they shouldn’t. That means someone (probably you) will have to put on rubber gloves, a clothes peg on the nose, and disassemble the pump to clean it out and reassemble. It’s quite unpleasant.

Plus if you get frozen in in winter – even if you’re in a marina this can happen on your mooring – you won’t be able to move the boat to a pump-out dock which can mean you have no capacity for using the toilet once it’s full! For this reason, boats with pump-out tanks often also carry a compact portable toilet as an emergency backup, since that can be carried to any Elsan point like the cassette type described above.

In the last few years, a more environmentally-friendly, ecological form of toilet has grown in popularity – the composting loo, strictly better referred to as a separating toilet. This has its bowl designed such that liquid waste – wee, in other words – gets directed into one (removable) tank while solids – poo – get dumped straight down into the bowels of the toilet, if you’ll forgive that expression, generally into a plastic liner.

Separating the waste in this way gives the solids a chance to dry out, usually assisted by a fan which runs permanently from the solids tank to outside the boat, and in doing so begins to break them down into compost.

The liquid waste is dumped – by you, by hand – at any Elsan point or public toilet facility or (arguably) into the nearest hedge although there are rules about it not being dumped within ten metres of a water course so you may find you’re dumping it on private land and that leads us onto trespass so maybe just find an Elsan point eh?

Because the solids are drying out and take up relatively little space compared to the liquid, the tank will typically last for several weeks before it’s full.

Here’s where the argument for boat composting starts to fail a little; in theory the solids will have composted to the point where they can be dumped into a hole dug on any bit of land. In practice, this will only be true, at best, for the first waste that was in the tank while more recent deposits will still be very much in their raw state.

Until recently, it was said to be acceptable to dump human faeces into the general waste bins provided by the CRT – yes, really – provided that it was double-bagged. In order for it to stay contained, that means plastic bags which rather undoes the environmental credentials of the toilet.

That has now been disallowed by the Trust and you must not put such waste in the general refuse bins. Unfortunately, no suitable alternative facilities have been put in place.

In an ideal world, you’d take the solids out of the loo, in their (plastic!) liner and leave them somewhere warm on the boat for several months to compost properly. If it’s done fully, that waste really can be buried in a hole with no issues. Who on earth, though, is going to keep several months’ worth of composting poo on their boat?

In summary, the composting system is a nice idea but as it’s impractical to fully and properly compost the waste on a boat, and you can no longer put it in the onshore waste bins, it’s become impractical. Even when you could dump the waste, you were really just putting bagged sewage into the ground which rather defeats the environmental credentials of the concept.

The ultimate mobile toilet must surely be one that simply reduces the waste to a tiny pile of ash and that’s the promise of incinerating toilets. They burn the waste using gas or electricity and leave just one teaspoon of ash from four people after a week of use[4]. That ash is said to be free of bacteria and environmentally friendly.

There are some drawbacks, of course, and by far the biggest one is price; such a toilet costs several thousand pounds compared to a few hundred for the alternatives. They also use a considerable amount of gas so be prepared to have extra gas bottles on the boat. Gas is expensive too.

Electric versions are available such as the Separett “Cindi” but they use a considerable amount of power[5]; as electricity is in short supply on most boats, this version would probably be impractical unless you have a modern boat with big lithium battery bank, large inverter and a generator to boot.

Users have also told me that because the toilet uses no water for any kind of flush, you’re required to place a paper liner into the bowl before each use, rather like a coffee machine filter. This catches the waste and drops it into the incineration chamber as one “package”! So it’s a little bit fiddly in operation.

[1] Strictly speaking, Elsan is a company brand name (see but has passed into generic use amongst narrowboaters to mean a portable toilet system particularly with respect to the disposal points.

[2] Provided they’re not out of action due to inconsiderate boaters tipping unsuitable waste down them which seems to happen with tedious regularity.

[3] Like the Elsan points, the CRT pump-outs are also often out of action and subject to much boater complaint.

[4] Figure from Cinderella Incineration Toilets

[5] Separett quote a draw of 1.8kW which many boat inverters could handle but the per-incineration power use of 0.6 – 2.4kWh equates to a maximum of 200Ah from a 12V system; for a lot of narrowboats that would be the entire battery bank capacity (or more!) gone in a single flush. A generator could be run to supply it but having to do so every time you use the loo seems somewhat excessive in my opinion.