How Does a Well Work – The Ultimate Guide

Last Updated on December 14, 2022 by Mattias

Most people in the world get their water from a central supply system, which then goes through pipes to get fresh water from their tap. However, those who aren’t connected to the centralized water get their water from public or private water wells.

Wells are essential to building a sustainable society and provide a reliable and clean water source that can be used for your daily needs like drinking, irrigation, and bathing.

More than 23 million households in the United States use private wells for drinking water, according to the EPA. And all well owners can enjoy the freedom of no water bills, which those with city water can’t escape.

How Does a Well Work?

Before we got all the fancy equipment we have today, wells were dug by hand. Today drilling machines can create much more uniform and far deeper wells.

A well is just a hole in the ground below the water table. But before going any deeper in understanding how a well works, we will go through groundwater and aquifers.


Groundwater is the water beneath the surface we’re all walking on and can be found in the spaces and cracks in soil, rock, and sand. The groundwater is renewed when water moves down and refills the depots, for example, during rainfall and snow melting. It represents 95% of all freshwater, except the ocean and frozen water. 

The groundwater recharging depends on different environmental aspects. It goes through natural filtration but can be contaminated, which makes it essential to protect it from pollutants, according to the national ground water association.


An aquifer exists underground, holds groundwater, and contains rock or sediment layers.

When a well is built, the main goal is to get deep enough into the aquifer so water can be pumped out by using a well water pump.

It’s hard to say how deep a well needs to be since sometimes an aquifer can be found a few feet down, and others can be found hundreds and even thousands of feet down. 

Types of Water Wells

There are three different types of wells. Let’s take a closer look at each one of them.

Dug Wells

Dug wells are typically dug with hands or simple tools. This method is only possible In places with high water tables and soft ground. 

Once the water table is reached, the hole is typically lined with stone, bricks, or tile to stabilize it. These wells generally can’t be much deeper than the water table itself, as you can’t dig past the water table with a shovel. The hole will keep filling in. 

This is the same phenomenon you likely experienced when digging a hole in the sand at the beach. A dug well is mostly between 10 and 30 feet deep. 

Today modern dug wells are dug by much better equipment and are mostly lined with concrete tiles. 

They usually have a larger diameter than the hand-dug wells and go far more profound.

However, mostly they don’t have any continuous casing and are shallow, which makes them sensitive to contamination.

A dug well can run dry if the water table drops below the bottom during a drought.

Drilled Wells

Most modern wells are drilled. Drilled wells are probably the most common type today, but they’re also the most complicated and expensive to build. 

They are drilled using massive rigs, which can go through all types of earth. These wells are typically very deep, upwards of 1,000 feet, and are used to reach very deep-water reserves. 

The pump is often placed in the well, pushing the water to the surface.

Driven Wells

Driven wells are simple to construct and don’t cost so much. They are made from small diameter pipes driven into the soft ground. 

These pipes typically have screens at their bottom to filter out sand and particulate matter and can be effective quick, straightforward ways to make a well.

However, they have some drawbacks since they only can reach shallow water, and contamination from the surface can easily occur. Typically, a driven well is between 30 to 50 feet deep.

Read also: How Fast Does Well Water Replenish? An Easy Explanation

Well Water System Components

Well Casing

A well casing is needed to keep dirt and excess water from entering the well, which can cause bacterial contamination. It’s usually made of stainless steel, carbon steel, or polyvinyl chloride (PVC). The tube-shaped structure provides a pathway for the water to move from the aquifer to the land’s surface. 

It forms the well’s structure and shapes while maintaining its opening. An empty area is filled with concrete between the untreated sides of the well, preventing the casing from moving. 

Well Caps

Well, caps are placed on the top of the well to prevent insects, debris, or small animals from getting inside and contaminating the well. 

They are mostly made of plastic or aluminum. A vent is included to control the water pressure during well pumping.

Not only will they block things from coming inside, but also from anyone falling in. 

Well Screens

Well screens are found in the bottom of the well casing and filter the water from dirt, rock, sand, or other sediments trying to get inside the well while also letting water flow through.

The most common well screens are slotted pipe, perforated pipe, and continuous slot. They are constructed to be placed within the saturated portion, preventing damage if the groundwater level goes down. 

Pitless Adapter

A pitless adapter works like a connector, allowing the pipe that water travels through to remain below the frost line. Therefore, creating a frost-proof seal between the well casing and the waterline, so the water won’t freeze. 

A check valve may be installed below the adapter to prevent water from pouring back into the well. 

Well Pump

The well pump’s purpose is to pump water from the well into your house. The water is pushed through a jet or pipe with the help of an electric motor. Today, jet and submersible pumps are the most common due to their popularity. The type of well pump required depends on the depth of the well and the amount of water a household needs. A well pump can last for a long time if handled correctly.

Read also: How To Prime a Well Pump – Step By Step

Submersible Pumps

A submersible pump can be used for wells as deep as 400 feet or as shallow as 25 feet. They are submerged deep in the well, below the water level. This type of pump pushes water upwards with the help of an impeller instead of pumping water from above as jet pumps do. 

They are practical, durable, and adaptable. Thus it is used by the most modern water wells systems. 

Jet Pumps

Jet pumps are installed above ground and use centrifugal force to pump water from the well. It’s mainly used for shallow wells, which are 25 feet or less. The water is drawn by a suction pipe, which creates a vacuum using an impeller that drives the water through a small nozzle. 

Jet pumps use water to pump water. Therefore, they need to be primed with flowing water. 

Centrifugal Pumps

A centrifugal well pump is simple and much smaller than the other well pumps. Making them easy to maintain and access when needed. They are best suited for wells 25 feet deep or less. They transport the water by using the kinetic energy of a motor. 

Hand pumps

A hand pump draws water from a well by using a hand-cranked lever. Hand pumps aren’t so common, but they are suitable for off-grid since they don’t need electricity. 

Pressure Tank

The pressure tank is essential for the well system to work. It’s needed to maintain water pressure throughout the system and store reserve water, so the pump doesn’t need to go on and off every time it is on. 

Pressure tank sizes are between 40 gallons for domestic use and up to 21,000 gallons for industrial use.

Pressure is created by pumping water into the tank until the tank’s air is compressed to 40-60 PSI.

By using an air compressor, the air pressure is maintained. The air pressure forces water out of the tank when the valve is opened via a faucet. 

Pressure Switch and Control Box

Well, pumps aren’t designed to go 24/7, especially submersible pumps, since it would cause unnecessary use on the pumping mechanism and increase the electricity cost. 

The pressure switch and the control box work together with the pressure tank to measure the well’s water pressure

So when the water pressure drops below a specific level, the pump turns on.

Since the ideal water pressure is between 40-60 PSI, the pressure switch turns the pump on when the pressure drops below 40 PSI. 

Therefore, bringing water pressure back up within range. The pressure switch turns the pump off when the water pressure is restored at a specific level. 

Read also: Pressure Switch For Well Pump Adjustment 101

Things to Know Before Building a Well System

If you’re considering building a well system, there are a few things you need to know first. So you can get a well that works properly and can provide fresh water.

Get Aware of the Land

Getting to know the land around the property is essential. 

  • Ask the well owners nearby if they’ve had any troubles or success with their wells. 
  • Get detailed information about the groundwater quality, how deep a well must be drilled, and if there’s any risk of low water levels during the year. The authorities can provide this information.
  • Ask around and research the climate since snow, flooding, and rainfall can cause problems. 
  • Are there any factories around? A factory can pose a huge contamination risk for your water. 

Pick the Best Location for the Well Site

One of the most important factors is the location of the well. The well can last long and give clean water by picking the perfect spot. Things to consider are the water yield and the risk of contamination. 

  • If there is an area with heavy rainfall, it’s better to pick a location on a higher level instead of a lower level of the ground. Because when the rain pours downhill, it will grab and carry contaminants in the water. This means that if the well is at a low level where rainwater collects, there is a high risk of pollutants entering the groundwater through the well. 
  • Always choose a well located at a higher ground level if the home has a septic tank. It also needs to be at a distance since there may be a risk of contamination if the septic tank leaks. 
  • As we covered above, ensure there aren’t any places or objects that can contaminate the well, like livestock, barns, pens, creeks, streams, or septic tanks. 

Obtain the Required Permits

Before starting, you must get the necessary permits, which is essential if you’re hiring a contractor since they won’t create if you

can’t show proof of all licenses. Each state and region has its rules, so look up the rules of where you live first. 

If you’re considering drilling your well on your own, read: All You Need To Know About Digging Your Own Well In The 50 States In the USA.

Calculate How Much Water Your Household Needs

By calculating how much water your household uses, you can get the best type of well pump.

According to EPA, the average family uses more than 300 gallons of water.

Knowing the exact numbers, you can determine the best well pump and pressure tank for your well system. 

How to Maintain Your Well

Doing well inspections annually is essential to ensure that your water source is clean and also to prevent expensive and inconvenient 


Therefore, we recommend all well owners keep a detailed log with the following: 

– Well system details 

– Depth of the well 

– Current water level

– Information about the equipment

Because if a contractor needs to respond to a service call, the information will make everything much more accessible. 

Additional Tips

  • Always contact a qualified professional when service is needed. Never do it yourself. 
  • Learn and practice preventive maintenance, which will pay off in the long run. 
  • Learn how a well works before getting help. 
  • Keep chemicals away from the well.
  • When installing or drilling a well, ensure that the persons are certified. 
  • Inspect the well cover or well cap so it’s in good shape. 
  • Have a long enough separation from your well, waste systems, and the place you store all chemicals. 

Contaminants In Your Well Water

A well can get contaminated easily if it isn’t built correctly or if any toxic pollutants leach into it. But even if it’s perfectly made, it can still get contaminated. 

If harmful materials are dumped or spilled near your well site, they may enter the aquifer, contaminating the groundwater.

Potential Contamination Sources 

  • Microorganisms 
  • Nitrite & nitrate
  • Heavy metals
  • Organic chemicals 
  • Radionuclides
  • Flouride

How to Test Well Water

How Does a Well Work Summary

I hope you enjoyed this article.

As you have discovered, a well works incredibly if you ask us.