Everything you ever wanted to know about urine and composting toilets

Ever wondered where urine goes in a composting toilet? Do you have to dispose of it? Does it smell? We answer all these questions and more.

Number one. Wizz, pee, wee wee, leak, tinkle, snow ink, p-mail or a Bear Grylls margarita, no matter what you call it, we all do it, and usually several times a day. Typically we don’t have to give urine a second thought if it’s flushed away to a sewage processing facility or perhaps puddled on the side of the road on those extra-long road trips. Still, when you have a composting toilet, you’re 100% responsible for managing your and your family's waste. 

Some might look at this as a little ‘icky’, but for those of us who have taken on the responsibility of managing waste – be it to save water or to get off the grid, dealing with urine is something we need to think about. But how do composting toilets deal with urine? We’re glad you asked. 

Dealing with urine in a composting toilet

Composting toilets deal with urine in, essentially, two different ways. Either urine is evaporated from your composting toilet via an exhaust fan or it’s collected in a separate container and disposed of or used. 

Using an exhaust fan to deal with excess liquid

Many composting toilet models have exhaust fans as part of their overall design. These are used to regulate several important elements of a composting pile including keeping air flow moving around the pile, moving any smells away from bathrooms and into the atmosphere and also to help evaporate any liquid in your composting toilet. 

Human waste, both number ones and twos are made up predominantly of liquid (approximately 75% of stools are made of water) so it’s important to reduce the liquid content of your composting pile to ensure optimum performance of all the microorganisms, fungi and bacteria that are breaking down waste into usable, top-soil-like byproduct. 

An exhaust fan is powered either by plugging it into mains power or hooking it up to solar. This fan constantly rotates to keep air moving through your composting toilet unit and helps reduce the amount of liquid in the pile by evaporation. 

Using a urine diversion toilet

Some composting toilets (like the Pasadero Urine Diverting Pedestal, EcoLet™ NE Separera 30 and the Nature Loo™ Mini) can separate urine either into a container or into a gravel absorption trench. This helps keep liquid content in the composting pile to a minimum as only solid waste is added to the pile. 

Having the urine diverted enables customers to have a smaller, lower wattage fan for their system, which may benefit areas where sunshine is not as prevalent to charge any solar systems connected to the exhaust fan. 

Does urine smell in a composting toilet?

If your composting toilet is set up properly and it’s working the way it should, there should be no smell coming from your composting toilet. A strong smell of urine or black waste is typically an indication that something isn’t working correctly in your toilet. This could be due to:-

  • Too much liquid in your pile
  • Broken exhaust fan
  • The exhaust fan moving slower than it should
  • Something blocking the pipe where the exhaust fan is located
  • Reduction in bacteria and microorganisms from:-
    • Elongated periods of no use
    • Use of chemical cleaners
    • Foreign objects added to the toilet

If you collect it, what can you use urine for?

It’s really only in the past few hundred years that we’ve been moving away from using natural products and byproducts like urine and replacing them with chemical ingredients. In the past, urine was used for a wide range of different applications, from fertiliser and gunpowder to teeth whitener and leather softener. 

These days, we don’t need to use urine to make explosives or clean our clothes, but it makes an excellent fertiliser for those looking to help their gardens grow. If you look at the chemical makeup of urine, it’s chock full of nitrogen, phosphorus, potassium and trace elements for plants and can be used on your garden composting pile or diluted with 10-15 parts water and used on lawns, shrubs and trees. 

If you’re thinking about purchasing a composting toilet and can’t decide between a ‘traditional’ composting toilet or a urine-diverting composting toilet, we hope this article has given you some food for thought. If you’re still unsure, you can always give one of our representatives a call on 1300 138 182.