elevated tank

GC: n

CT: Storage tanks are an important part of any distribution system. Water can be pumped into the tank during periods of low demand and then pumped out of the tank into the distribution system during periods of peak demand. In addition, storage tanks can provide the water pressure in the distribution system.
The two types of storage tanks are ground level tanks and elevated tanks. Elevated storage facilities are also divided into two types – standpipes and tanks. In this section, we will consider the pros and cons of various types of water tanks.

S: http://water.me.vccs.edu/courses/ENV110/lesson10.htm (last access: 26th December 2014)

N: 1. elevated (adj): Past Participle of verb to elevate, late 15c., “to raise above the usual position,” from Latin elevatus, past participle of elevare “lift up, raise,” figuratively, “to lighten, alleviate,” from ex- “out” + levare “lighten, raise,” from levis “light” in weight. Sense of “raise in rank or status” is from c.1500. Moral or intellectual sense is from 1620s. Related: Elevated (which also was old slang for “drunk”); elevating.
tank (n): 1610s, “pool or lake for irrigation or drinking water,” a word originally brought by the Portuguese from India, from a Hindi source, such as Gujarati tankh “cistern, underground reservoir for water,” Marathi tanken, or tanka “reservoir of water, tank.” Perhaps ultimately from Sanskrit tadaga-m “pond, lake pool,” and reinforced in later sense of “large artificial container for liquid” (1680s) by Portuguese tanque “reservoir,” from estancar “hold back a current of water,” from Vulgar Latin stanticare. But other sources say the Portuguese word is the source of the Indian ones. Meaning “fuel container” is recorded from 1902.
2. A tank, used for storage in a water distribution system, which is raised above the surface of the ground and is supported by posts or columns.
3. Elevated tanks have many advantages. Elevated tanks do not require the continuous operation of pumps. Short term pump shutdown does not affect water pressure in the distribution system since the pressure is maintained by gravity. And strategic location of the tank can equalize water pressures in the distribution system. However, precise water pressure can be difficult to manage in some elevated tanks.
The pressure of the water flowing out of an elevated tank depends on the depth of the water in the tank. A nearly empty tank probably will not provide enough pressure while a completely full tank may provide too much pressure. The optimal pressure is achieved at only one depth.
The optimal depth of water for the purpose of producing pressure is even more specific for standpipes than for tanks elevated on legs. The length of the standpipe causes continual and highly unequal pressures on the distribution system. In addition, a significant quantity of the water in a standpipe is required to produce the necessary water pressure. The water below a certain level is therefore used only as a support, unless booster pumps are available for emergency use of this water.
4. Do not confuse the terms “water tower”, “elevated reservoir” and “elevated tank”. “Water tower” and “elevated reservoir” are synonyms; both these terms have a wider extension of meaning than “elevated tank”.
5. There are two types of elevated reservoirs: standpipes and elevated tanks.
6. Cultural Interrelation: We can mention, for instance, the Riverside Elevated Water Tank located in Williamsburg (Virginia) and the McKenzie Elevated Tank situated in South Mesquite (Texas).

S: 1. OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=elevate&searchmode=none; http://www.etymonline.com/index.php?allowed_in_frame=0&search=tank&searchmode=none (last access: 26th December 2014). 2. TERMIUM PLUS (last access: 31 March 2015). 3. http://water.me.vccs.edu/courses/ENV110/lesson10.htm (last access: 26th December 2014). 4 & 5. TERMIUM PLUS (last access: 31 March 2015). 6. http://www.fmi-dallas.com/projects/water/mckenzie-elevated-tank/ (last access: 31 March 2015); http://www.timmons.com/projects/riverside-elevated-water-tank (last access: 31 March 2015).

SYN: elevated water tank, above-ground tank.

S: TERMIUM PLUS (last access: 31 March 2015)

CR: reservoir