Portable Toilet

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Portable Toilet

Background

The portable toilet is a lightweight, transportable, efficient and more sanitary variation of a common facility for the elimination of human waste that existed before the advent of indoor plumbing—the outhouse. Before indoor plumbing allowed for the development of a system for transporting human waste from a receptacle to a sewer system through a series of pipes and other plumbing apparatus, humans often attended to their need to eliminate waste in an isolated stall located outside of living and working quarters, if they elected to use any type of structure at all. Typically, this stall contained a bench with a large hole cut into it. The waste was deposited through the hole directly to the ground below. A more refined version of the outhouse was the water closet, an indoor facility with a water tank and flushing system that deposited the waste in a cesspit below.

The advent of indoor plumbing led to the development of the first modern toilet in 1843, although toilets hooked up to sewage systems did not come into general use until the Victorian era when modern sewage systems began to be constructed. Still, this innovation was not useful for those who worked or otherwise congregated in outdoor areas with no access to such a facility. Some such venues, such as many roadway rest areas, camping facilities, and children's summer camps, still utilize rustic outhouses. Since at least the 1960s, many other venues, especially those where populations congregate only for temporary periods, have featured lightweight, sanitary portable toilet facilities—easily transportable, private, individual plastic stalls containing toilets, each with its own independent sanitary system consisting of rudimentary plumbing, a holding tank, and sanitizing chemicals.

Portable toilets are most commonly used at construction sites, outdoor parking lots, and other work environments where indoor plumbing is inaccessible, and at large outdoor gatherings such as concerts, fairs, and recreational events.

History

The earliest known toilet facilities date back to the third millennium b.c. Rudimentary lavatory facilities have been discovered in the form of recesses in stone walls of houses in Scotland dating back to around 2,800 b.c. Around the same time, it appears that Western-style lavatory facilities were being constructed from bricks with wooden seats in Pakistan. Sewage fell through a chute to a drain or cesspit. In Egypt, toilets have been found in the bathrooms of tombs, presumably for use in the afterlife. The first portable toilet dates back to the mid-fourteenth century b.c. In Egypt, a wooden stool with a large slot in the middle for use with a pottery vessel beneath it was discovered in the tomb of Kha, the senior official of the Thebes workmen's community.

Until the eighteenth century, the portable chamber pot, a slightly more modern variation of this first portable toilet, was the most commonly used lavatory facility. The notion of a flushable toilet was developed by the Elizabethan poet Sir John Harington, who designed an indoor water closet containing a toilet facility that could dilute sewage with water contained in a cistern. This invention was significantly enhanced by Thomas Crapper, who in 1886 created the first flushable toilet featuring a water tank placed high above the toilet bowl to actually flush out the contents of the bowl, rather than merely dilute them. As public sewage systems became more developed, Crapper's invention became common.

In the twentieth century, inventors have combined the portability of the more ancient lavatories with the sanitary benefits of the modern toilet to create a contained system that is also compact, lightweight, and transportable. The portable toilet, commonly called the Porta-John after one prominent manufacturer of this product, is now a common feature at work sites and events that do not have access to sewer systems.

Raw Materials

Portable toilet assembly is relatively simple and few materials are needed. The main component of the facility is light-weight sheet plastic, such as polyethylene, which forms the actual toilet unit as well as the cabana in which it is contained. A pump and holding tank form the portable sewage system. These items are fastened with an assortment of screws, nails, rivets, bolts, and hinges. The facility is also equipped with a chemical supply container and inlet tube.

The Manufacturing
Process

The toilet unit

1 The toilet unit is comprised of rigid, lightweight sheet plastic, which is formed into a box-like structure and secured with nuts, bolts, and rivets. The top sheet contains an opening for placement of the toilet tank. The top sheet may not be secured with these permanent fixtures, allowing for its easy removal to clean the tank. A lock may be placed over the top sheet to prevent its unauthorized removal.
2 The actual toilet tank, which is placed in this unit, is made of the same material and shaped with a flat, corrugated front wall and rounded rear wall. The upper edge of the toilet tank is formed as a peripheral flange that extends outward and downward.
3 The toilet tank is fitted with a cover formed of two flat semi-circular plastic sheets. The lower sheet has a peripheral edge lip that extends downward, the upper sheet has a front lip that extends downward, and the rear lip extends upward and outward to latch onto the peripheral flange of the toilet bowl. Both sheets are fitted with a central toilet opening.
4 A conventional toilet seat made of plastic is placed over the toilet bowl and connected to the assembly with hinges.
5 The seat is fitted with a pin, which pushes upward against a metal wear plate, which is secured to the bottom surface of the seat. The pin extends downward through the cover and a bracket. Under the bracket, a coil spring is placed around the pin. The upper end of the coil engages a washer fastened to the pin so that the seat maintains an upright position when not in use. (Note: Not all portable toilets are flushable. Those that are not do not contain this or the following two steps in the manufacturing process, but merely contain chemicals in the holding tank.)
6 A piston is placed underneath the lower end of the pin, and a mechanical, bellows-type pump is placed beneath the piston. The pump contains a spray opening and is connected to an inlet tube which is, in turn, connected to a chemical supply container. When the seat is raised, the piston will activate the pump.
7 The toilet opening is fitted with a pair of flat, plastic doors secured by hinges to bosses fastened to the bottom of the tank. These doors are connected to the toilet seat with metal links so that they are activated when the seat is lowered and raised.

The cabana

8 A cabana is formed with two lightweight plastic side panels, a similar back panel, and a front panel with a door opening. All parts are secured with nails, screws, bolts, and rivets. A variation of this model uses interfitting joints, so that the facility can be disassembled and reassembled for easier transportation.
9 A rounded top and a flat bottom containing a depression for the toilet tank, and a drain to release moisture are secured to the structure with rivets.
10 A vent pipe is placed through a small opening in the roof and another small opening in the toilet holding tank.

Additional features

11 A plastic door is fitted with an inset handle and a sliding lock that activates a "vacant-not vacant" sign on the reverse side of the door.
12 The door is attached to the front panel with hinges.

Byproducts/Waste

The contents of portable toilet holding tanks must be disposed of in accordance with state and federal environmental regulations. Typically, the chemicals used to sanitize the portable toilet facility are biodegradable and, thus, are not subject to any special disposal requirements. The waste in the holding tanks must be disposed of like any other form of sewage which is subject to local, state, and federal regulation. For example, in Michigan, portable toilet waste may be discharged to a publicly-owned treatment works (POTW) facility through the local sewage system or land-applied on farming property. Both of these activities require permits. The waste may also be transported to the POTW, which does not require a permit but does require approval of the POTW.

The Future

Portable toilets will most likely be necessary as long as humans continue to congregate in outdoor areas and other sites without indoor plumbing. While this product is fairly simple, it is subject to innovations, especially with regard to design. For instance, at least one company manufactures a portable toilet facility constructed with removable joints, which allows for easy disassembly of the unit and enhances its transportability. Alternatives to chemical sanitizing solutions are also in the works. At least one company already manufacturers an organic solution that deodorizes and sanitizes in the same way as the commonly used chemical solutions.