It may seem surprising but, some people use urine for aquaponics and it is becoming a real topic. After all, urine is natural and could allow to close the loop, integrating human waste in food production. Ok, I can already see some checking heads. Before being carried away let’s see the 7 points below:
1. Urine is a good source of ammonia
Urine is composed of 95% water. The other main components is urea (9.3 g/L).
Urea formula is CO(NH2)2. In the aquaponics system (like in the soil), many bacteria will convert urea into ammonia (thanks to the urease enzyme).
Therefore, Urine is a very good indirect source of ammonia. (more information here: https://en.wikipedia.org/wiki/Urea)
2. Urine is sterile
The general believe is that urine is dirty. But in reality, for a human in good health, urine is sterile. It doesn’t contain bacteria but it doesn’t necessary mean that urine is safe… See point 3 here below:
3. There are hazards associated with urine for aquaponics
If urine is sterile, it can however contain all sorts of chemicals. If you are taking drugs, those drugs will eventually be evacuated trough your urine. This is the main reason why I don’t recommend peeing in your aquaponics system. It can obviously damage your health but also the physiology of your fish. There are several rivers in the world (such as the Thames in England) where the fish population has switched to mainly females. This is due to the contraceptive drugs used by humans and rejected to the river through urine… More information here: https://www.independent.co.uk/news/uk/home-news/male-fish-are-being-feminised-by-river-pollution-1446764.html
4. Your aquaponics system may not need urine…
While urine is a good source of ammonia, it is probably not necessarily needed in your aquaponics system. A well-established grow bed aquaponics system will often generate more nitrogen than it can use. I often recommend checking the nitrate level. Here is a video and article on this topic (https://aquaponicsrevolution.com/nitrate-in-aquaponics; https://youtu.be/-ACp9Bp4NKo. The only time where an adjustion of ammonia or urea is beneficial is at the very beginning. During the cycling process. But as explaines in this video: https://youtu.be/2kYmCpVPXO4 It is probably safer to use fish food for this purpose.
5. What about your image?
Ok I know, most of us don’t really mind about what other think, but still… Would you feel comfortable to give some strawberries to your neighboors and tell them: “Enjoy the strawberries, they are grown with love, I pee on it every morning”? I know we don’t pee directly on the plants but, however I am sure you see where I am coming from. It may seem stupid, but I wouldn’t be comfortable to do that.
6. Where to add urine in a simple growbed aquaponics system?
If adding urine, I would add it in the fish tank directly. Not that the fish would like it but it would be ok at small quantity. The reason why I would add it in the fish tank is because I would never add it directly in the growbed. I would be scared to spray the leaves that I will consume later… Yes, I am not really keen on the idea to consume my own pee. What about you? J
Generally I add minerals directly in the bell siphon as it’s a perfect location to mix and dissolve minerals. In the instance of urine, it’s already a liquid composed of 95% water so it will easily mix with the whole volume of water. No need to specifically add it into the bell siphon.
7. A system relying on urine only?
Some systems rely on urine such as peeponics or even bioponics but it is different to aquaponics. In aquaponics we rely on the fish to release nitrogen in their waste to “power” the whole ecosystem. Peeponics and bioponics don’t involve fish. That is the reason why an alternative source of nitrogen is required.
In conclusion I can understand why people are using urine to cycle the system. It is free, natural and allows to close the food cycle. However, I am part of those people who prefer to remain away from urine use in aquaponics. Don’t get me wrong, I love the idea of using human waste. I believe we can collect it in dry toilets and use it as a tree fertiliser without concern. I just don’t feel comfortable with using human pee in my loved aquaponics ecosystems.
You may have another opinion, please give me your feedback 🙂
you will probably be interested to discover Jonathan’s six steps to build and manage an Aquaponics system. Click here to access for free! Thanks and good reading 🙂