These use a special sterilizing chemical, which flushes through the lavatory pan and kills the odours of the sewage. Such toilets work without water, but generally need some power if the chemical is to be recirculated to act as a flushing agent. The systems work well, and are used most on temporary sites where self-contained trailer units are provided, but can also be used on permanent sites. The chemical renders the sewage sterile, so it can be stored for long periods if need be. It must be pumped out periodically and disposed of in a suitable location; exceptionally it can be discharged into a soakaway if permission or licence to do so can be obtained.
In terms of sustainable development there is a question over the appropriateness of using and disposing of large quantities of sterilizing chemicals anywhere in the environment. For this reason this type may not be widely favoured.