A portable or mobile toilet is any type of toilet that can be moved around, some by one person, some by mechanical equipment. Most types do not require any pre-existing services, such as sewerage disposal, but are completely self-contained. They can be used in a variety of situations, for example in urban slums of developing countries, at festivals, for camping, or on boats. One well-known type of portable toilets are chemical toilets, but other types exist as well, such as urine-diversion dehydration toilets, composting toilets, container-based toilets, bucket toilets, freezing toilets and incineration toilets. A portable toilet is not connected to a hole in the ground, nor to a septic tank, nor is it plumbed into a municipal system leading to a sewage treatment plant; it can, by definition, be picked up and moved. Some portable toilets can be carried by one person, as in the main image, whereas others need heavy lifting equipment such as a truck and crane.
Types
Chemical toilets
A chemical toilet collects human excreta in a holding tank and uses chemicals to minimize the odors. These chemicals may either mask the odor or contain biocides that hinder odor-causing bacteria from multiplying, keeping the smell to a minimum. Chemical toilets include those on plane and trains, as well as much simpler ones.
Portable camping toilets
A simpler type of portable toilet may be used in travel trailers and on small boats. They are also referred to as "cassette toilet" or "camping toilet", or under brand names that have become generic trademarks. The Oxford English Dictionary lists "Porta Potti" as "A proprietary name for: a portable chemical toilet, as used by campers", and gives mostly American examples from 1968. The OED gives this proprietary name a second meaning, "a small prefabricated unit containing a toilet, designed for easy transportation and temporary installation esp. outdoors", which Wikipedia covers under chemical toilet. The other name common in British English is "Elsan", which dates back to 1925. According to the Camping and Caravanning Club, "Today you will often see campsites refer to their Chemical Disposal Points as Elsan Disposal Points because of the history and popularity of the brand." The Canal and River Trust uses both brand names, in lieu of any unbranded term. One colloquialism for these simple toilets is the "bucket and chuck it" system, although in fact they no longer resemble an open bucket. These are designed to be emptied into sanitary stations connected to the regular sewage system. These toilets are not to be confused with the types that are plumbed in to the vehicle and need to be pumped out at holding tank dump stations.
Urine-diversion dehydration toilets
Portable urine-diversion dehydration toilets are self-contained dry toilets, sometimes referred to as mobile or stand-alone units. They are identifiable by their one-piece molded plastic shells or, in the case of DIY versions, simple plywood box construction. Most users of self-contained UDDTs rely upon a post-treatment process to ensure pathogen reduction. This post-treatment may consist of long-term storage or addition to an existing or purpose-built compost pile or some combination thereof. A post-treatment step is unnecessary in the case of very modest seasonal use.
A slang term, now dated or historic, is a "thunder-box". The term was used particularly in British India; travel writer Stephen McClarence called it "a crude sort of colonial lavatory". One features to comic effect in Evelyn Waugh's novel Men at Arms:
