What do I do with the solids when the toilet is full?

This depends a lot on your circumstances. For many people the simplest solution is to empty the contents to an existing or newly installed composter – to be used with other garden and kitchen waste once composted. For others it is stored in bins supplied with the toilet until fully composted and then either added to the garden or disposed of with waste (typically in green wheely-bins).

For those living and moving continuously in boats or motor-homes the solution is usually storing the bins in a locker or engine room until fully composted and then either digging into a local field (with permisssion) or bagging and disposing at a rubbish point. Those with friends or family with gardens or allotments can often persuade them to accept their fertile offerings.

How long will it take for the solids to break down into compost?

The breakdown of human faeces into harmless compost starts to happen within the toilet, especially if the toilet is not in continuous use. The speed with which this happens varies largely dependent on the warmth of the environment. In warm conditions this can be 6 months, whilst in colder conditions it can take as long as a year. For this reason we encourage storage of composting material in a warm place, or adding it to an existing composter, where other kitchen or garden waste can assist with composting. For those wanting to break their waste down in the shortest time, we recommend the ‘Aerobin composter‘. This well designed product encourages high temperatures in the compost and can render human waste as compost in as little as 90 days if well managed.

In order to ensure that all pathogens or other harmful bacteria are neutralised, the Environment Agency advise that such compost material should be kept on site for 26 weeks, but after that time it can be removed to another site or disposed of in domestic refuse or recycling systems.

How can I dispose of the urine?

This depends on your circumstances and whether you are a keen gardener. For many people the easiest solution is to run the urine directly from the toilet into a small soakaway in the ground. In most situations, this only needs to be about 500mm x 500mm filled with gravel and usually finished off with grass on top. Since the urine is going immediately into the ground and is excellent fertiliser, having a high nitrogen content, there is no smell from the soakaway and plants nearby will thrive on the added nutrients.

For keen gardeners, it may be preferable to collect the urine. This can then be removed for use either directly around plants or added to a composter to improve composting. Alternatively, by diluting with water to avoid damaging delicate leaves, the mixture can be sprayed over plants. This can improve crop yields dramatically as shown by many trials, especially those carried out in the USA and Africa – 8 fold increases have been reported.

For those in mobile applications the urine can be disposed of simply by pouring it under a hedge or in the undergrowth either on the towpath, the river bank or at the roadside. Since urine is sterile and counts as grey water, this is quite legal and adds useful nutrients to the soil as well as removing most of the volume of human output. In this way mobile users can avoid the need to search for disposal sites and minimise the volume of storage space required.