Although toilets are often the subject of much humor and ridicule, they are clearly a plumbing fixture that most of us would find difficult to live without.
History of Toilets
Toilets date back as far as 2500 B.C. in India. Indian cities such as Harappa and Mohenjo-daro had sewage systems that connected to toilets in every home. Other civilizations had flush toilet technology as well, but most of the technology was lost after the fall of the Roman Empire. Sir John Harington is credited with the invention of the flush toilet around 1596. Harington's design, called the Ajax, used a design with a tank and bowl; a flush valve emptied water from the tank, and a wash-down design emptied the bowl. In 1775, the S-trap was invented by Alexander Cummings. This system used standing water in the toilet's bowl to prevent the escape of odors from the sewer, and is the basis for the design of most toilets today.
How Toilets Operate
In a typical toilet, water is emptied from the tank into the bowl upon flush. Gravitational pressure from the volume of released water causes a siphon action in the S-trap, which allows the water to be emptied. The flush valve system, which is connected to the home's plumbing, fills with water until a set point. This resets the system for another flush.
Single-Piece vs. Two-Piece Toilets
There is a wide variety of toilets available today. In choosing a toilet, there are several decisions to consider. Although most toilets come in two separate pieces -- the tank and the bowl -- there are also single-piece toilets available. One-piece toilets are usually more attractive and easier to clean, but they tend to be more expensive. If self-installation is planned, consider also that lifting each piece of a two-piece toilet will likely be more convenient than lifting an entire single-piece assembly.
Varieties in Toilet Shapes and Toilet Styles
The shape of the bowl can be either round or elongated in front. Choose a round front if space is an issue -- they are more compact than the elongated front design. An elongated design allows extra comfort when seated. The overall size of the toilet is also an important consideration. Also, consider the cosmetics of the toilet. Many toilets are available as part of a kit, which includes matching fixtures to provide for a uniform look among the bathroom pieces.
Toilets: Flush Pressure
As previously mentioned, standard toilets operate on a siphon system. An alternative to the standard gravity siphon system is the pressure-assisted toilet. In this design, the tank has a supply of pressurized air, which is released upon flush and allows for a more powerful flush. Despite their robust operation, these toilets are generally noisier, more difficult to repair, and more expensive. However, they might be a good choice if the standard 1.6 gallon flush is not adequate.