Toilets | Research & Encyclopedia Articles

About 3 pages (854 words)

Toilet Summary

Toilets

The origin of the indoor toilet for the disposal of human wastes goes far back in history. Archaeologists found in the palace of King Minos on Crete an indoor latrine that had a wooden seat and may have worked like a modern flush toilet; they also discovered a water-supply system of terra cotta pipes to provide water for the toilet. Between 2500 and 1500 B.C., cities in the Indus Valley also had indoor toilets that were flushed with water. The wastewater was carried to street drains through brick-lined pits. In 1860, Reverend Henry Moule invented the earth closet, a wooden seat over a bucket and a hopper filled with dry earth, charcoal, or ashes. The user of the toilet pulled a handle to release a layer of earth from the hopper over the wastes in the bucket. The container was emptied periodically. During the eighteenth and nineteenth centuries in Europe, human wastes were deposited in pan closets or jerry pots. After use, the pots were emptied or concealed in commodes. The contents of the jerry pots were often collected by nearby farmers who used the wastes as organic fertilizer. However, as cities grew larger, transportation of the wastes to farms became uneconomical, and the wastes were dumped into communal cesspits or into rivers. The flush toilet common in use today was supposedly invented by Thomas Crapper in the nineteenth century; Wallace Rayburn wrote a biography of Crapper, titled Flushed with Pride, in 1969.

The development of the flush toilet was primarily responsible for the development of the modern sanitary system, consisting of a maze of underground pipes, pumps, and centralized treatment systems. Modern sanitary systems are efficient in removing human and other wastes from human dwellings but are costly in terms of capital investment in the infrastructure, operational requirements, and energy requirements. The treated wastewater is usually disposed of in rivers and lakes, sometimes causing adverse impacts upon the receiving waters.

Sanitary systems require an abundant supply of water, and the flush toilet is responsible for the largest use of water in the home. Each flush of a conventional water-carriage toilet uses between 4–7 gal (15–26 L) of water, depending on the model and water supply pressure. The average amount of water used per flush is 4.3 gal (16 L). Since each person flushes the toilet an average of 3.5 times per day, the average daily flow per person is approximately 16 gal (60 L) for a yearly flow of 5,840 gal (22,104 L).

To reduce the volume of water used for flushing, a variety of devices are available for use with a conventional flush toilet. These devices include:

Tank insert - a displacement device placed in storage tank of conventional toilets to reduce the volume (but not the height) of stored water.
Dual flush toilet - devices used with conventional toilets to enable the user to select from two flush volumes, based on the presence of solid or liquid waste materials.
Water-saving toilet - variation of conventional toilet with redesigned flushing rim and priming jet that allows the initiation of the siphon flush in a smaller trapway with less water.
Pressurized and compressed air (assisted flush toilet) variation of conventional toilet designed to utilize compressed air to aid in flushing by propelling water into the bowl at increased velocity.
Vacuum-assisted flush toilet - variation of conventional toilet in which the fixture is connected to a vacuum system that is used to assist a small amount of water in flushing.

In addition to modifications to conventional flush toilets, non-water carriage toilets are available to reduce the amount of water required. They are also used for disposing of toilet wastes. Types of non-water carriage toilet systems include:

Composting toilet - self-contained units that accept toilet wastes and utilize the addition of heat in combination with aerobic biological activity to stabilize human excreta; larger units may accept other organic wastes in addition to toilet wastes and requires periodic disposal of residuals.
Incinerating toilet - small self-contained units that utilize a burning assembly or heating element to volatilize the organic components of human waste and evaporate the liquids; requires periodic disposal of residuals.
Oil-recycle toilets - self-contained unit that uses a mineral oil to transport human excreta from a toilet fixture to a storage tank; oil is purified and reused for flushing; requires removal and disposal of excreta from storage tank periodically (usually annually).

The wastes from toilets are referred to as "blackwater." If the wastes from toilets are segregated and handled separately using alternative non-water carriage toilets from the wastewaters generated from other fixtures in the home (referred to as "graywater"), significant quantities of pollutants, especially suspended solids, nitrogen, and pathogenic organisms, can be eliminated from the total wastewater flow. Graywater, though it still may contain significant numbers of pathogenic organisms, may be simpler to manage than total residential wastewater due to a reduced flow volume.