Why your composting toilet smells bad and what you can do about it

Why your composting toilet smells bad and what you can do about it
Table of Contents

Composting toilets don't smell because they do two things: they separate your business into solids and liquids and embed the solids in dry wipes or, more accurately, dry litter. With good drying, regular emptying and proper cleaning, the only odeur your nose will detect is the smell of the particular litter you are using. 

"My composting toilet smells. What's the cause?" "Counter question: do you occasionally flush the urine canister with water?" "Yes, every now and then, after emptying it." "You see, that's the crux of the matter, or the canister's urine scale!"

When it comes to the topic of "my composting toilets smells," the dialogue is almost always the same. But why does the liaison of water and pee stink so much and what can you do to prevent the two from running into each other in the first place?



The formation of urine scale

When lime combines with urine, a chemical reaction occurs. The result is urine scale. Since tap water always contains lime, the formation of urine scale is unavoidable. On the one hand, yellow-brown deposits are formed that grow over time and are difficult to remove, and on the other hand, odors are formed.

Preventing urine scale means preventing that your composting toilet smells 

If you want to avoid that your composting toilet smells, never use pure water to rinse and flush your urine canister. Instead, use diluted acetic acid (1:7 or stronger) or diluted citric acid (max. 3 tablespoons to 1 liter of water). Alternatively, ph-neutral cleaners or agents containing effective microorganisms are also suitable. The urine canister should be emptied every two to three days. The longer you wait to empty it, the more likely it is that bacteria will form, which also cause odors.



What to do if the urine scale is already there and the composting toilet smells?

If urine scale has already collected in your canister, it can be removed with vinegar essence rinses. It may take a few rinses until all residues are removed. However, you will notice that the odor will gradually dissipate.

What is the difference between vinegar essence and vinegar? 

Vinegar essence is more concentrated than vinegar. Wine or apple cider vinegar contains up to 15% acid, while vinegar essence contains 25%. Thus, the pH value of vinegar is also lower than that of vinegar essence. While vinegar is produced from apples, wine or brandy by fermentation with alcohol, the production of vinegar essence takes place synthetically. For regular cleaning of your Trelino®, acetic acid is absolutely effective and sufficient.

By the way...

Not only the canister, but also the solids container or the separator insert can be cleaned very well with diluted acetic acid. As a practical aid, we recommend a spray bottle: simply apply a few sprays of the solution to the separator insert and then wipe with one or two sheets of toilet paper. Your Trelino® will be fresh and ready for the next use. If you like citrus oil scents, you can also use fresh sprays for the separator insert as an alternative or supplement.


What if the composting toilet smells at the back?

The solids bucket of your composting toilets smells when the big business does not dry well enough. There are various reasons for this.

Maybe your composting toilet smells because don't use enough litter. Depending on the consistency, you need more or less litter to dry out the liquid. That is, the more liquid the session turns out, the deeper you may reach into the litter bag. If Montezuma's revenge hits you with monsoon-like force, it makes sense to empty the solids bucket after the session. Refrain from using unnecessary moisturizers like a douche or damp toilet paper. For the freshness kick afterwards, there are alternatives made of foam, which can be dosed well and do not develop so much moisture.

If you are on the road in the summer and your composting toilets smells, the reason is often condensation. Urin kind of condensates at high temperatures, rises in your composting toilet, "rains down" on your solids and moistens them again. In this case, it helps to connect a fan that can extract the moisture. 

We have summarized everything you need to know about cleaning your dry separating toilet in a video. Have a look. After that you know what to do to avoid that your composting smells.

With this in mind: No matter whether No. 1 or No. 2., just be happy with your loo.


  • Inge Lihl

    Wie ist die beste Reinigung des Membranverschlusses?
    Wie oft sollte er gewechselt werden?
    Vielen Dank für die Antwort
    Trelino® Composting Toilets replied:
    Hallo Inge,  vielen Dank für Deine Nachricht. Bei der Silikon Membranlippe handelt es sich um ein Verschleißteil, welches aufgrund der Materialbeschaffenheit (Silikon), sich mit der Zeit abnutzt. Nach ca. 3 Monaten (bei Dauergebrauch) empfehlen wir den Austausch der Membran. Zudem empfehlen wir eine Reinigung mit (verdünntem) Tafelessig (ca. 10 % Säure) und nicht mit Essigessenz (ca. 27 % Säure).  Einen großen Unterschied macht das Einfüllen des Essigs. Sobald Essig regelmäßig durch die Membran geschüttet wird, beginnt sie ihre Form zu verlieren. Es empfiehlt sich, den (verdünnten) Essig daher nicht durch die Membran zu schütten, sondern direkt in den Kanister. Das Schwenken des Urinkanisters, bei der Reinigung, reinigt und verlängert auch die Lebensdauer der Membran. – Viele Grüße vom Trelino Team.  ​ On Mon, 5 Feb at 1:57 PM , Sunny <sunny@comment.sunnysideapps.com> wrote:

  • Cees

    Graag betere vertaling naar Nederlands! Hier is meestal geen touw aan vast te knopen
    Trelino® Composting Toilets replied:
    Hello Cees, Hartelijk dank voor uw waardevolle feedback.   

  • Norbert

    Leider fällt in unserer Trelino-Toilette häufig der Membranverschluss in den Urinbehälter. Das wäre wahrscheinlich nicht der Fall, wenn der obere Rand des Membranverschlusses breiter wäre. Habt ihr darüber schon nachgedacht?
    Trelino® Composting Toilets replied:
    Hallo Norbert, vielen Dank für Deine Rückmeldung und die Idee. Es hilft, wenn Du beim Einsetzen des Oberteils, den vorderen Bereich zuerst ablegst und dann erst den hinteren Bereich. Produktionsbedingt ist der Trichter des Urinbereichs manchmal etwas lang. Es kann helfen, diesen etwas zu kürzen. Liebe Grüße – Justyna – Team Trelino® 

  • Mario Oeffner

    Bitte um Erläuterung, warum bei der Reinigung im Gegensatz zu Essigsäure bei Zitronensäure eine so geringe Konzentration (3 EL auf den Liter Wasser) verwendet werden soll. Ich bevorzuge nämlich Zitronensäure, weil sei besser riecht.

    Beste Grüße aus Erpel
    Trelino® Composting Toilets replied:
    Hallo Mario, die Verdünnung der Zitronen- oder Essigsäure kannst Du selbst definieren. Je nach Anwendung kann die Konzentration kleiner oder größer sein. 1 EL Zitronensäure verdünnt in 1 L Wasser ergibt eine Säurekonzentration von 5 %. Demnach hast Du bei 3 EL eine Säurekonzentration von 15 %. Dies reicht aus, um eine Trenntoilette zu reinigen. Im Übrigen hat der klassische Tafelessig eine Säurekonzentration von 5-10 %. Liebe Grüße Justyna – Team Trelino®

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