How to find the right urine separator for your composting toilet

Which divider is the best for you?

Find out which composting toilet insert is best for you to build your own garden toilet, weekend home toilet or camper van toilet.

In this article, I would like to introduce you to the most common divider inserts for dry toilets.

Since I wrote this blog post last year, a lot has happened in the field of composting toilets, dry toilets and composting toilets. And that's a good thing.

It shows that dry composting toilets are gaining attention as garden toilets and in the area of motorhomes and weekend homes and are replacing chemical toilets more and more.

To keep you up to date, I have revised the article.

If the principle of the composting toilet or the dry composting toilet is not yet clear to you, take a look at this blog article: How a composting toilet works.

This blog post is structured as follows:

  1. Principle of the composting toilet (dry composting toilet). How does the composting toilet actually work?
  2. Which urine separator are available?
  3. Advantages and disadvantages of the individual composting toilet inserts
  4. What should you bear in mind when building your own composting toilet?
  5. My conclusion
  6. The most important facts at a glance
  7. Further links

In this article, I will talk about how divider toilets are constructed, what you can expect for your money, and what advantages and disadvantages they have.

With one of these "separators", each of you should be able to build your own composting toilet. The only thing missing is the bucket and the urine container.

1. What is the separation insert for?

The composting toilet consists of three essential components. On the one hand, we have the actual separating insert, which separates the liquid from the solid, as well as the containers for the urine and for the solid.

The urine separator is the heart of every separation toilet. The purpose of this insert is to cleanly separate urine from solids.

The separation ensures that the excreta do not mix.

The advantage: the individual excretions do not stink and your toilet is odour-free.

Why is this so? Urine does not smell as long as it does not decompose.

The solid matter does not smell either if it is well dried. Most people use an appropriate litter for this purpose (e.g.: small animal litter).

Depending on the degree of use, you should also equip the separation toilet with a fan. This ensures that excess moisture is transported out of your toilet and thus supports faster drying.

The better the separation works, the less work you will have with your separation toilet later on.

Are you looking for more detailed information on how the separation toilet works? Have a look here!

How a composting toilet works

2. what urine separator are available for dry toilets?

There is now quite a wide range of divider inserts for divider toilets. Depending on where your separation toilet will be used, e.g. in a motorhome, as a garden toilet or in a weekend house, this will result in recommendations.

The most popular divider inserts for portable toilets, composting toilets and dry toilets on the market are currently:

  • Separett Privy 501 (500 and 400)
  • Trelino - Extra flat divider insert
  • Trelino separator inserts S / XL
  • Free Range Design from GB
  • Tractor hopper from the hardware store

In the following sub-chapters you will find detailed information on all separator inserts.

To the overview of all divider inserts

3. Advantages and disadvantages of the individual inserts for separation toilets

I'd like to start with the most popular and best-known urine separator for composting toilets:

Privy 501, Privy 501 with seat, Privy 500, Privy 503 and Privy 400 separettes

Separett currently offers 5 different variants of divider inserts. Some of these are available in grey or blue. The following divider inserts are shown from left to right:

  • Privy 501 without toilet seat
  • Privy 501 with toilet seat
  • Privy 500 with hard foam toilet seat
  • Privy 503 with wooden toilet seat
  • Privy 400 divider without seat

The separet divider inserts come from Sweden. That is, from the country where the composting toilet/dry toilet is very widespread and popular.

Separett has therefore had a very long experience with the subject of separation and composting toilets. In addition to separation inserts, Separett also builds completely finished separation toilets.

Over the years, the products have been further developed and improved. All urine seperator have the same basic shape. They differ in whether they can be supplied with or without a toilet seat.

Only the Separett Privy 501 divider inserts are slightly rounded at the front to disappear under the toilet seat.

Buy separating insert now

The Separett Privy divider inserts can be purchased as a divider insert only or with a plastic or wooden toilet seat. The divider inserts can be purchased without a seat from 83,- EUR.

The scope of delivery also includes a 2.5 m long spiral hose to drain the urine into an appropriate canister and an adapter to enlarge the urine area.

This is an additional plastic part that you can optionally click into the rear area of the divider. With this adapter, the urine area is enlarged by approx. 1 cm and extended to the rear.

Depending on the sitting position, this can be advantageous. In addition, the rear edge is raised by approx. 1.5 cm. This provides improved protection against urine flowing into the solid waste container.

You should remove this component regularly during use and clean it accordingly. Otherwise, the additional part here forms a very nice, high edge that safely drains the urine to the front.

But as I said, you don't have to use the insert element. Just try it out.

The divider is quickly installed in the previously sawn-out hole in your enclosure using four screws. A template is included in the delivery.

And if you haven't sawn out the hole quite so precisely, you won't be able to see anything later, because the divider insert has a large edge and is inserted from above. Made by injection moulding, it has a high production quality.

With a very smooth surface which makes cleaning very easy. The grey is of course not as dirt-sensitive as a comparable white divider insert.

The material polypropylene (PP) is insensitive to acidic cleaning agents and very resistant overall.

Nevertheless, cleaning should be as gentle as possible so as not to damage the particularly smooth surface.

The divider itself is available in grey or blue. This allows you to design your separation toilet in the way that best suits your environment.

You can find all versions under divider inserts

here in the shop

TRENNTO - Extra flat divider insert (unfortunately currently not available)

Trenneinsatz flach_Seite

This separating toilet insert is currently the newest and flattest on the market.

Originally intended for use with our own built separation toilets, especially for the more compact ones, this separation insert is now also available for the DIY sector.

The divider inserts are deep-drawn from PVC. They have a wall thickness of approx. 5 mm and are therefore very stable. Due to the manufacturing process, the surface is very smooth - from above and below - and is easy to clean.

Due to the material, the divider insert is very resistant to environmental influences and cleaning agents based on citric acid or vinegar essence.

The rim of the XL version was deliberately kept very large so that you can cut it to size.

This has the advantage that you can create a homogeneous surface without edges on your toilet.

I can also show you the example of the Trennto designer toilet.

Trelino® oval and XL - separating inserts - latest generation

In addition to Separett, there are now also other separating inserts from Trelino. Until now, however, it was not possible to buy the separating toilet inserts separately here. That has now changed. That's why I'm introducing you to this urine separator.

I think the Trelino is a good alternative to the ones listed above.

This separating toilet insert is made of ABS with a PMMA coating. This makes them very stable and of high quality.

The particularly smooth surface allows dirt to almost roll off. The layout is similar to that of the Privy from Separett. The only difference is that no insert wedge is used here to extend the urine tray.

There are two sizes of privy inserts. Depending on which toilet seat you decide on later, the divider insert disappears very well under the toilet seat. It is very stable and really easy to install.

The insert is available in white. Especially with the white version, your future toilet will look very similar to a normal household toilet.

Personally, I think that the Trelino divider is a very good and inexpensive alternative.

You can get the Trelino composting toilet insert from 99 EUR here in the shop.

Free range design divider


The Free Range Design separation insert comes from the UK.

The company currently only offers the funnel, otherwise it does nothing in the area of dry or separation toilets. The insert is available in white or black. Both can be purchased via Amazon for 40 EUR.

A small installation manual in English comes with the delivery.

These instructions also explain the ideal installation point.

The funnel is the front urine collector.

A small sieve is supplied with the insert. Probably for collecting the kidney stones. Unfortunately, you can't really get the strainer stuck unless you use superglue.

In my opinion, the funnel could be a little bigger so that the whole thing fits women better.

The shape of the funnel also creates a drip edge, which means that something can quickly flow down into the toilet without being noticed.

This is a simple deep-drawn part. As it looks, it is drawn from a square piece of plastic. Depending on the use, the sides should still be cut to size.

The surface is a bit wavy due to the manufacturing process. The funnel is not quite as stable as the one from Separett or Trelino, but it is not as expensive.

You can install it pretty much as you like, but you may have to shorten the edges a little. Standard toilet seats can also be used here.

The divider insert from Free Range Design is available here on Amazon.

Have a look at all divider inserts here: Overview of all divider inserts in the shop.

Tractor funnel as a divider

If you really want to save money, I would like to introduce you to this alternative... I once found this idea in a forum and for the sake of completeness I would like to share it with you.

A tractor funnel for filling oil.

Yes, you have understood correctly. It is a funnel from agricultural supplies.

The funnel has more or less similar dimensions to the separator insert from Free Range Design. And it also has the sieve. The funnel is available in different colours on Amazon.

It is also a plastic deep-drawing part.

The catchment area is relatively narrow and therefore not really well suited for women. I also don't find it really visually appealing. But if you are looking for something really cheap, you can adapt it for your purposes.

But beware, there are a few things to keep in mind: The funnel has a very small rim, so assembly is a bit difficult. There is not much space left for the screws.


It also builds very far into the depths. This means that a correspondingly shallow bottle or canister must be found. Or the toilet housing must be correspondingly high.

However, if you simply attach a hose for drainage, you can certainly manage with this.

By the way, the funnel is available for 12.70 EUR here at Amazon.

4. What to bear in mind during installation

Women and men are anatomically different. This is especially true when using a divider toilet. You should pay attention to the optimal positioning of the divider insert. It's best to test pee beforehand.

It's also important that we boys don't use the toilet standing up, because that's guaranteed to go wrong. But that should go without saying. The more upright you sit on the toilet, the better you can aim. So just practise a bit.

By the way, this also applies to the ready-to-buy toilets.

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5. My conclusion

There is currently a good variety of separating inserts for DIY construction of your separating toilet, dry toilet and composting toilet. Whether for your garden shed, weekend house or mobile home. Depending on your preferences and budget, there is something for everyone.

For me, the inserts from Separett are one of the better alternatives. They are stable, well thought-out and have a good product quality. The Separett impresses with its combination with toilet seat, is inexpensive and in the new grey colour also quite attractive.

Due to the combination with the toilet seat, this insert is also somewhat larger. So be sure to note the dimensions if you have little space.

The Trelino divider has been redesigned and optimised. It looks good, is very compact and also works well for women.

Are you looking for a urine separator for a flat composting toilet? For this purpose we have the Extra Flat Separator in our shop.

If you want to save a lot and are creative, you can also choose a funnel or urine separator version.

6. Key facts at a glance

Separett Privy

Material: injection moulded polypropylene
different versions available:
  • 501 without seat
  • 501 with toilet seat
  • 503 with wooden seat + lid
  • 500 with hard foam seat
  • 400 only urine separator
including spiral tube & sawing template
quick and easy installation (4 screws)
very smooth surface
urine area can be enlarged with Privy separation inserts by clickable plastic part

TRENNTO - Extra flat divider insert (currently not available)Trenneinsatz flach_Seite

  • Material: PVC, deep-drawn
  • very smooth surface
  • very stable (wall thickness 5 mm)
  • insensitive to acidic cleaners, such as diluted vinegar/lemon cleaners
  • good proportions, high urine edge of the urine separator
  • flat design for low urine trap toilets
  • currently not available

Trelino® separating insert

  • Material: ABS / PMMA
  • very stable and high quality
  • very smooth on top
  • compact design and well suited for narrow composting toilets
  • alternatively also available as XL to cut to size yourself
  • easy installation
  • in white, various sizes from € 99.90

Free Range Design

  • very inexpensive variant
  • consists only of the urine funnel
  • from GB with English assembly instructions
  • a bit short - could be problematic for women
  • surface a bit wavy and not as stable as Separett or Trelino
  • 40,- € at Amazon

Tractor hopper

  • creative and cost-effective variant
  • is a misappropriated use
  • not well suited for women, as very narrow
  • assembly somewhat difficult - very small rim for screws
  • due to its deep design, it needs a very shallow urine tray or a high toilet bowl
  • Alternatively drain the urine with a hose
  • 12,70 € at Amazon

View all divider inserts now

You can also get the dividing inserts in practical do-it-yourself sets:

Overview: View all kits.

What kind of separating insert do you have in use? What is important to you? Do you have any questions that are still unanswered here?

Write to me in the comments section. I'm looking forward to it.

Your Markus

7. Further links

7. more links

PS: If you want to know more about the advantages of composting toilets and dry toilets, also read this blog article.

PPS: Are you interested in self-build reports? Click here - Here I am adding examples from users bit by bit.

And if you are interested in a complete separation toilet. Check out this blog post of mine: The 6 Best Separating Toilets for Motorhomes, Garden Houses and TinyHouses.

Also check out the MySeparatingToilet YouTube channel. There you will find many videos about separation toilets and separation inserts.PS: Wenn Du mehr über die Vorteile von Trenntoiletten und Trockentoiletten wissen möchtet, lies auch diesen