Why Are Water Towers So Tall


 

Long before you enter some towns and cities the first thing you may notice bright-colored elevated water tanks that mark the different communities standing high in the sky visible for miles. Why are water towers so tall?

A Water Tower holds a water tank engineered at a height sufficient to keep constant pressure on the whole water system for the distribution of potable water & to provide storage for fire protection, filling up at night when demand is low & acting as a buffer when demand is higher during the day.

By using simple calculations city engineers and planners can keep Water Towers filled and part of the Water Distribution system in case of demand or backup in case of an emergency.

 

How Are Water Towers Built

Water Towers and Standpipes as they are sometimes referred to, are different-shaped elevated water tanks that do the same thing which is to keep a network of water systems pressurized. The elevation of the tanks enables the pressure without the use of pumps.

The source of the treated water is pumped to certain PSI (pounds per square inch) back where the water is treated and that pressure pushes the water up and fills the Water Tank.

If the Water Tower tank is 115 feet in the air and the Water Treatment Plant’s pump use 50 lbs of pressure to fill the tank, (that pressure is called Head)  

The pump needs 50 lbs of PSI that would provide 2.131 ft. of Head in order to move the water in the pipe from the Water Treatment Plant up to and fill the Water Tower.

With this calculation township and city, engineers can plan on how high the elevation and capacity, the tower needs to be to keep the system pressurized on one side of the Water Tower.

Once the Tower is filled then the outlet of the Water will deliver PSI on the other side. Each 1 foot of water on the other side can deliver .43 PSI to the system. So if the Water Tower is storing 100 Feet of Water in the Tower it will produce .43 PSI with no energy from mechanical pumps. 

Water usage changes during the course of the day. The need fluctuates normally during peak hours that are during the day and fewer demand hours overnight. Adding other Water Towers can be used to buffer that demand by keeping a bigger supply available during peak hours and keeping water at a constant rate.

They also ensure pressure and flowrate if an emergency arises when a pump breaks down on the system. This is also planned in the design to manage the system properly.

The Water Towers can help regulate the flow, decrease the strain on the system, store excess water for emergencies, and serve as backups to keep the demand for Water satisfied.

Keeping this supply of water under pressure and regulated also can help it stay clean by keeping water from laying stagnant in the pipes reducing the chance of bacteria from developing.

Many different types of materials can be used to construct a typical water tower like steel and reinforced or prestressed concrete are most often used (with wood, fiberglass, or brick also in use), incorporating an interior coating to protect the water from any effects from the lining material.

They can be constructed on hills close to or inside the community to give the added height that will be configured into the elevation to add Head to the system.

 

When Was the First Water Tower Built

Since the beginning of man, water was carried and kept for man to use and didn’t take very long for ancient man to figure out that it was needed and not always at their doorstep or cave entrance. They invented ways of carrying it from one location to another.

This happens today in countries where Water Scarcity is an issue. People mostly women spend hours or even days collecting water for families or whole villages to drink or use for their daily needs. It’s just not an efficient way of doing it.

The first type of what today is called infrastructure as open channels that carried water to be used in ancient cities from outside sources. Not much different than it is done today. Ditches canals or Aqueducts are dug out and water is moved by gravity it can work up to many many miles from its source.

This is also still being used throughout the country like in California where water and weather contribute to Water Scarcity issues.

Gravity and open flow that control these water systems can contribute to pollution and problems that have existed for many years. Thankfully most water distributors use pipes and Water Towers that eliminate these and other problems moving fresh clean water from region to region depending on Pumps and gravity to satisfy most of the demand for the precious life-sustaining water.

Much like automobiles, the shapes and styles of water tanks and towers have changed over the years as technology advanced. Older styles of water towers still dot the American landscape, although, as with the Model T, some of those older styles are no longer fabricated.

Standpipes were popular in the late 1800s to the early 1900s and the structures are still in use. The first reinforced concrete tank was built in Hull, Massachusetts in 1903. The Fort Revere water tower is an AWWA Historic Landmark.

Life spans of most early concrete tanks were relatively short compared to steel tanks, which, if they’re maintained well, can last 100 years or more.

Bigger cities like New York and Chicago found ways to use the large structures to blend into the city transferring them into art forms. When welding overtook rivets in steel building after WWII designing Water Towers became fashionable art as in the Water Tower at Warner Bros.

Studios Water Tower is a riveted witch’s hat built in 1927 along with a resemblance of the Tin Man from the Wizard of Oz.

Do Water Towers Freeze

In more extreme climates in the regions of the country water inside the Water Towers do freeze. Engineers that design and plan the construction used Heating Systems in the plans and designs with an emphasis on the central pipe that runs from ground level up into the bottom of the tank is called a riser. Water is pumped into the base of the riser and allowed to rise into the tank.

Many tank risers are wrapped with heat tape, covered with insulation, and capped by an aluminum jacket.  In addition, a heating system may be installed in an adjacent building or into the valve pit underneath the riser.

The heater introduces heated water or steam into the base of the riser.  All the heat naturally rises into the tank to slow and control freezing. Ice will form first on the surface of the water level in the Tower, some Water Tower owners use aeration to keep the water from the start of freezing.

Are Water Towers Still Used

People and communities still use water towers. In fact, every water system needs a water tower to provide water in case of an emergency. Water towers provide a vital role to make certain the water system in the municipal area is reliable and dependable.

The Towers even out the water pressure throughout the distribution system and can be an important asset supplying water when pumps are down. Most Water Towers can hold enough water for 24 hours demand of the community population.

Best of all Water Towers supplying to the community-run on gravity. This makes them more important in emergency situations besides the need for supplying water. This the reason that most people have never experienced a time when their town or city found themselves without water.

But mostly they will provide the safety of certain water pressure is needed for fire protection. Most Municipal towns and cities require a minimum pressure for portable water supply.

The water pressure in the Tower is always ready to go powered by gravity even if the lights go out because of electrical outages.  A water tower guarantees that there will be enough pressure to keep water flowing through the fire hydrants used by the fireman to save a home that would normally burn to the ground if not for that needed water pressure.

Fire insurance rates are normally lower in a community in which the water system has water towers.

That PSI water pressure is measured at the Water Tower and on the street where you live by a special measuring tool used by Utility Companies connected at the Water Hydrants. As a general rule it above 40 lbs. PSI (pounds per square inch) of needed pressure for fire protection on your street.

Water Towers are decorated and can have the logo for their city or town that they serve. The more water in the tank and the taller it is is engineered into providing the town or city that much more protection for fire prevention and larger supplies for power failures during storms like hurricanes where there are interruptions in utility services.

In New Jersey, they are used as a way to navigate small boats in the large Bays back into the town where you took it out.

 

Largest Water Tower

The water tower uses its height to supply that level of pressure to all of the houses and businesses in the area of the tower. So water towers are typically located on higher ground, and they are tall enough to provide the necessary pressure.

In hilly regions, a tower can sometimes be replaced by a simple tank located on the highest hill in the area. Some Cities like California use reservoirs that are higher in elevation and are gravity fed towards the city with some help of pumps that are strategically located along the way.

Most cities that have built skyscrapers and taller buildings will use Water Towers that are located on the roof of the structure. This water will provide potable drinking water and fire protection for the business or residents that are occupying them. The Union Watersphere, also known as the Union Water Tower, is a water tower topped with a sphere-shaped water tank in Union, New Jersey, United States, and characterized as the World’s Tallest Water Sphere.

Some places like California use a different strategy because of the dangers of earthquakes they rely on reservoirs like Hetch Hetchy north of SanFrancisco. There Water Towers are retired. But in most places around the country, they still are part of the American Landscape.

The Union Watersphere

The Hetch Hetchy Reservoir Feed San Francisco from a Higher Elevation

While water towers generally seem like the product of a bygone era, they’re still very much relevant today. The Louisville Water Tower in Kentucky, which was built in 1860, is the oldest surviving water tower in the country, and it’s still in use.

In New York City, millions of people still get water from water towers, though it’s one of the last of the large cities to rely on the Water Tower system. Stored on top of tall buildings, these water towers provide the pressure for water to flow even if the electricity goes off especially during a fire.

Water Towers are cleaned while they are in service.

Dive CArew Video Inside a Water Tower– shows the work inside the tank-like removing sediment that collects on the floor of the Tank. This is an excellent maintenance procedure that needs to be done on a regular basis. The sediment then settles in the tank of the Water Tank contains harmful bacteria and protozoa that could eventually contaminate the potable water supply.

Without a water tower, the municipality would have to buy a water pump big and powerful enough to keep up with peak demand in the mornings, which would then largely go to waste during less busy parts of the day for water usage plus incur extra costs. Some communities think it’s well worth the extra cost to have Waters Towers on their Water System.

 

Jim has worked in the Water/Wastewater and Water Utilities Business as an Operating Consultant for over 30 years and has written more than 300 articles on Water Problems and Solutions. One of the scariest jobs I had to do in my career was to climb a Water Tower.

JimGalloway

Author/Editor, MyWaterEarth&Sky

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