Water tower

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The mushroom-shaped concrete water tower of Roihuvuori in Helsinki, Finland was built in the 1970s. It is 52 metres high and can hold around 12,000 m³ of water.

A water tower or elevated water tank is a very large tank constructed for the purpose of holding a supply of water at a height sufficient to pressurize a water supply system. Many water towers were constructed during the industrial revolution and some of these are now considered architectural landmarks and monuments and may not be demolished. Some are converted to apartments or exclusive penthouses.

In certain areas, such as New York City, smaller water towers are constructed for individual buildings.

1 Construction
2 Purpose
3 Operation
4 Decoration
5 Declining use
6 Further uses
7 New York City
8 Famous towers
9 See also
10 External links

[edit] Construction

A typical water tower is constructed of steel, reinforced or prestressed concrete or bricks. It is usually spherical or cylindrical and is approximately 50 feet (16 metres) in diameter. It typically has a maximum height of approximately 120 feet.

[edit] Purpose

The users of the water supply (a town, factory, or just a building) need to have water pressure to maintain the safety of the water supply. If a water supply is not pressurized sufficiently, several things can happen:

Water may not reach the upper floors of a building;
Water may not spray from a tap with sufficient flow
Without a water tower, parts of gravity flow water supply systems in hilly areas may be subject to negative pressures (see siphon). Negative pressure in the system may cause shallow groundwater to be sucked into a leaky water supply system, polluting it with microorganisms, dirt, sand, fertilizers, and any other toxic contaminants that may be in the groundwater;

[edit] Operation

How Roihuvuori water tower works:
1. Pump station
2. Reservoir
3. Water user

The height of the tower provides the hydrostatic pressure for the water supply system, and it may be supplemented with a pump. The volume of the reservoir and diameter of the piping provide and sustain flow rate. However, relying on a pump to provide pressure is expensive; to keep up with varying demand, the pump would have to provide a constantly varying output pressure (and thus need an expensive control system) and it would have to be sized sufficiently to give the same pressure at high flow rates.

Very high flow rates are needed when fighting fires. With a water tower present, pumps can be sized for average demand, not peak demand; the tower can provide water pressure during the day and the pumps can refill the water tower at night when demand is very low.

[edit] Decoration

The House in the Clouds in Thorpeness functioned as the town's water tower until 1923.

Water towers can be surrounded by ornate coverings including fancy brickwork, a large ivy-covered trellis, etc., or it can be simply painted. Some city water towers had the name of the city painted in large letters on the roof, as a navigational aid to aviators. Sometimes the decoration can be humorous, as Granger, Iowa has two water towers, labeled HOT and COLD. The The House in the Clouds in Thorpeness was built to resemble a house in order to disguise the eyesore, whilst the lower floors were used for accommodation. When the town was connected to the mains water supply, the tank was dismantled and converted to additional living space.

[edit] Declining use

In many countries water towers have been taken out of the water supply system and replaced by pumps alone.

Water tower by V.Shukhov - the world's first hyperboloid structure, Russia, 1896	Typical U.S. water tower, Fort Sill, Oklahoma.	The local water tower at Grandview in Hampton, Virginia.	The Victorian water tower on Shooters Hill, London.
Modern U.S. water tower in Carmel, Indiana.	Unique water tower in the shape of a ketchup bottle, Collinsville, Illinois (This is also the world's largest ketchup bottle.)	Modern U.S. water tower in Bellaire, Texas.	The Westfield water tower.
Old water tower in Colmar, France.	Water tower - Gödöllő, Hungary	Water Tower - Gyöngyös, Hungary	1960s water tower shaped like a cone, Tonwell, Hertfordshire

[edit] Further uses

Some water towers are also used as observation towers. There are even water towers with restaurants, such as the Goldbergturm in Sindelfingen, Germany. It is also common to use water towers as the location of transmission mechanisms in the UHF range with small power, for instance for closed rural broadcasting service, portable radio, or celluar telephone service.

[edit] New York City

Water towers are ubiquitous in the New York City skyline

In the 1800s, New York City required that all buildings higher than 6 stories be equipped with a rooftop water tower. This was necessary to prevent the need for excessively high pressures at lower elevations, which could burst pipes. In modern times, the towers have become fashionable in some circles. As of 2006, the neighborhood of Tribeca requires water towers on all buildings, whether or not they are being used. Two companies in New York build water towers, both of which are family businesses in operation since the 1800s.^[1]