Why Must The Water Pump Be At The Bottom Of A Deep Well?

For safe drinking water, submersible pumps in deep wells are the way to go.

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by Steve Willson

According to the U.S. Census, more than 80 percent of Americans live in urban and suburban areas, while the remaining 20 percent are considered rural residents. The differences between these two groups are large and many, including the availability of some public services, like water and sewer pipes. Of course, these essentials are part of village government offerings in every corner of the U.S.

But once you live outside the village limits, homeowners (to say nothing of rural farmers and ranchers), usually have to supply their own. These residents may not need to pay water and sewer bills, but this is true only because they have already spent many thousands of dollars to install these services for themselves. Fortunately, both of these systems are long-lived and don’t require much care.

Septic systems are not mechanical. They succeed by putting gravity and bacteria to work underground. Wells, on the other hand, are more complicated and deliver water only via pumps. Generations ago, the standard rural pump was a hand pump that didn’t need electricity—just some old-fashioned elbow grease. By pumping the handle up and down, water is drawn from a well pipe that extends down into the groundwater.

These pumps worked great, needed very little maintenance and can still be bought today. They do suffer one serious problem, however. They can only lift water from a depth of 25 feet—no more and usually less. This is an issue of how high atmospheric air pressure can lift water. When the hand pump reduces the air pressure inside the well pipe, the surrounding atmospheric pressure forces the water up into and out of the pump. The higher the elevation, the lower the air pressure, and the maximum depth of water decreases.

Submersible Pumps

submersible well pump
A cylinder-shaped submersible pump fits inside a well casing and is lowered into the water at the bottom of the well. A water pipe, usually flexible plastic, is attached to the top of the pump and unrolls as the pump is lowered.

The same thing happens with two other shallow well pumps from days gone by: the piston pump and the jet pump. A water depth of about 25 feet is also the most these units can handle. Years ago, this was fine for many applications, including drinking water, because shallow groundwater wasn’t contaminated. Today, deep wells that deliver potable water are the standard, not only for purity but also for building permits, bank loans and real-estate contracts.

These wells are created by drilling a hole into the ground, through sandy soil and solid rock, until water is found. Depths between 300 and 500 feet are common. Typically, a 5- or 6-inch-diameter steel casing is driven into the hole to form the well, at least until it enters solid rock. Then a pump and motor cylinder (attached to supply piping) are lowered into the well until the assembly enters the water. The top end of the supply piping is connected to the water supply line in the house, and water is distributed throughout the structure.

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The reason the pump is lowered into the depths of the well is because it can push water up supply piping for many hundreds of feet. Air pressure will force the well water into the pump, but the pump will push it to the surface and beyond.

Pressure Tank & Switch

The pressure tank is located at the surface, usually inside a basement, and the water from the well is pushed into the tank by the submersible pump at the bottom of the well. This tank acts as a small storage tank so the pump is not activated if just a small amount of water is used. It also supplies pressure to the system so water reaches all the appliances and fixtures while providing enough force for an enjoyable shower or garden watering.
The pressure tank is located at the surface, usually inside a basement, and the water from the well is pushed into the tank by the submersible pump at the bottom of the well. This tank acts as a small storage tank so the pump is not activated if just a small amount of water is used. It also supplies pressure to the system so water reaches all the appliances and fixtures while providing enough force for an enjoyable shower or garden watering.

Once the water is pushed to the top of the well, it enters a pressure tank. These tanks, around 30 to 50 gallons, accomplish two jobs. The first is acting as a small storage tank. By holding several gallons of water, the well pump doesn’t have to start if somebody just wants a glass of water or to flush a toilet.

The standard tank pressure switch mounts on the tank or close to it and monitors the pressure inside the system. When it drops to a preset limit, it turns on the pump. When the pressure reaches the upper limit, it shuts off the pump.
The standard tank pressure switch mounts on the tank or close to it and monitors the pressure inside the system. When it drops to a preset limit, it turns on the pump. When the pressure reaches the upper limit, it shuts off the pump.

The tank’s second, more important job is to store its water under pressure. The top half of the tank is filled with pressurized air that forces water out when it’s needed and pushes it through the water supply pipes to water-using appliances, sinks, tubs, showers and toilets. Various tanks have different ways of separating the water and pressurized air inside the tank, but all the results are the same. The pump activates when an electric pressure switch mounted on the tank tells it to. As the water enters the tank, it compresses the air above the water and thus renews the pressure in the system.

Submersible water pumps have made it possible to easily access the clean water found in deep wells. For those in rural areas, they’re an indispensable solution for everyday life.

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