CAN I ADD URINE TO MY COMPOST?
Many gardening and composting sites recommend adding urine onto compost heaps to help speed things up. This basically means ‘taking a pee on the compost heap’. Here at the HOTBIN composting, we agree urine works well for cold (traditional) composting, but it is a definite No for the HOTBIN due to the nature of excess water – we go into a bit more detail below.
(Jump to this post if you are looking for advice on composing baby nappies).
WHY IS IT RECOMMENDED FOR COLD COMPOSTING?
Urine is about 98% water and the rest is mainly a chemical called urea. Urea is a source of ‘food’ and nitrogen for bacteria – they eat it. Because it is small molecules in a water solution – the bacteria can digest it very quickly which means heat is released quickly – this is good news so far!
WHY IS THE HOTBIN DIFFERENT?
There are two main home composting methods – hot and cold. Almost all the advice regarding urine is for cold composting. All composting releases water from the plant tissue. There are two places the water can go – it can drain into the soil or evaporate into the air.
In hot composting (and specifically in the HOTBIN), heat from the bacteria working (digesting) is used to remove this excess water from food waste. Adding more water (via urine) should therefore be avoided because you are just adding water to get a few grammes of urea (food). The extra water in urine is a huge negative in the HOTBIN – you end up needing to add another dry material to balance things – so a bag of shredded paper per half pint of urine.
In cold composting, you are accepting the water will drain in to the ground, and hence you are adding 2% (a few grammes) of nitrogen.
I READ SOMEWHERE YOU CANNOT USE FEMALE URINE OR URINE IF TAKING MEDICATION?
There are sometimes small amounts of antibiotics (if you are taking medication for urinary tract infections) or hormones (if you are taking contraceptive pills). Antibiotics and hormones are proteins. We are confounded by sites that state you cannot compost them – bacteria rapidly digest proteins!
CAN I ADD CAT PEE OR PET URINE?
The above applies for human pee, cat pee, dog pee and any other animal pee!
If you have pet bedding soaked in urine, it is OK to add in the HOTBIN because the exceptionally dry bedding (eg straw, saw dust, paper) balances the water in the urine.
HOW DO I GET THE HOTBIN WORKING FAST?
If you are struggling to get your waste hot, we have a number of posts on this topic – try how to get to 60C. It can be a little harder in winter as there is less waste, your best bet is to try a handful of chicken pellets rather than pee. You will add more nitrogen and more food (poo) for the bacteria and as pellets are dry so it avoids the issue of excess water. You can also kick start it in winter using the hot water bottle.