Choosing a composting toilet

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Choosing the right composting toilet can seem a little daunting when you first start to look at the ranges available. We hope this document will give you a little guidance and help you narrow the choice down. Don’t forget that we’re happy to chat to you either on the phone or by email if you need further help!

All the units we sell are based around a ‘urine separating’ system, also known as ‘waterless’ or ‘dry-toilets’ because they don’t flush or indeed use any water. Technically this is not 100% true as the occasional rinse with a cup of water down the urine tube will help reduce ‘latrine’ smells, but is not absolutely necessary.

Keeping the urine away from the poo means that the urine is classed as grey water – if you mix it with poo, it becomes black water and comes under different (stricter) regulations in terms of the environment because it’s more hazardous.

Taking the Pee!

The first thing to consider is what are you going to do with the urine when you use the loo?

If you’re on a boat, motorhome, caravan, or in a place where urine cannot be discharged into the ground, you’ll have to capture the urine and store it in a small tank, to be emptied in a suitable place daily or every few days.

If the toilet is fitted into a building, shed, permanent caravan, yurt, shepherds hut etc, then it’ll probably be more convenient to divert the urine outside the building and allow it to run into a soak-away pit (roughly 50cm x 50cm x 50cm hole, filled with gravel, stones or hardcore and covered with turf etc). You could also plumb the urine outlet into a standard household waste pipe (aka grey water pipe, such as the one that takes your used sink or bath water).

If you capture the urine, don’t forget that it also makes a great plant/tree fertiliser. Just dilute it around 8:1 and spread it around – any smells will soon disappear. Failing that, it’s also a brilliant compost activator – sprinkle on your compost pile to give it a nitrogen boost!


Choose your throne

The right toilet for you will depend on where it’s going to be located, your budget and in a way, your attitudes to dealing with ‘humanure’ and so on.

Keen to keep the costs low, or simply keen on DIY?

The Separett Privy 500, 501, Kildwick Klassic and Kompact urine separators are ideal starting points for your DIY compost toilet.

We used a Separett Privy when we first built our own compost toilet in our shed, although this system has now been replaced by an Eco-Loo Capture which has a Kildwick Klassic separator. The Kildwick is a high quality GRP, gloss white separator that enables you to use virtually any toilet seat and bucket etc to create your own throne.

You’ll need to consider how to box them in and whether to use a cover material or a fan for solids odour control. Check out our blog posts (Part One, Two and Three) which detail our own experiences of building a system based on the Separett Privy series.

Let us make your toilet?

We’ve been designing and building compost toilets based on various urine separators since 2012. Now we’ve pooled our experience into our own Eco-Loo range. Depending on how you are able or willing to deal with the urine, we have the Eco-Loo Capture (with built-in urine tank) or the Eco-Loo Divert, which as its name suggests, diverts urine away from the toilet and into a suitable soak-away or grey drain. We can supply the Eco-Loo Capture or Divert as ‘untreated’ and ready for you to paint or stain, or we can do that for you too, or you could look at the Kildwick Kabin or Separett Villa as ‘off the shelf’ solutions.

Location, location, location

You might have no choice about the location of the toilet, but bear in mind a few points which will help make installation and subsequent use easier. If you’re considering a Capture style toilet (either self-build or our own model) and are using sawdust as the cover material / odour control, then it can literally go anywhere because there are no connections to the outside world. If you want to use a fan for odour control (i.e. not use much/any sawdust etc.), then you’ll need to have an electrical connection nearby (either 12V DC or 230V mains) and the toilet will probably need to be against an outside wall so you can run the vent pipe through.

If you go for the Divert style (or your own version) then you’ll also need to run the urine to either a drain or soak-away pit, which may dictate where the toilet can go.

Ideally the vent pipe (on models with fans) should go out horizontally through the wall behind the toilet as this gives the shortest pipe run and therefore best efficiency. If this isn’t possible, you can take the pipe up higher and then out horizontally through the wall. The most complicated option is to take the pipe up through the ceiling and then out of the roof – for models running from 12 volts, you shouldn’t have more than 4 metres of vent pipe and a maximum of two 90 degree bends.


If you’re looking at a DIY solution, then the Separett Privy 500/501 and Kildwick Klassic/Kompact urine separators enable you to construct a solution customised for you needs, style and budget! The installation requirements of the urine separator can range from the simple to the elaborate – in it’s most basic form, all you need is box in the solid container, create a ‘seating’ area and do something with the urine pipe (as before, this can go into a mains drain, a drain pit in the ground, or collected for use as a fertiliser or for some other method of safe use/disposal) and that’s it.

However, the lack of vent pipe will mean the solid matter will not dry as fast and may be more prone to smells (the main reason for a fan and vent pipe is to create a low pressure over the waste bucket which will extract moisture, speeding up the drying and composting process and minimising any smells). You could rig up a vent pipe which used a small fan running from 12 volts.

As an alternative, you can also add a handful of dry organic matter, such as sawdust, fine wood shavings (often sold as pet bedding), to the bucket after each use as a cover material. This will help soak up any moisture and keep smells down. Please make sure the sawdust has not come from treated wood as this could be potentially dangerous to the environment and will almost certainly prevent the solid waste from composting properly.