How Does a Well Work? – Where Does Water Come From?

How Does a Well Work?

If you’re wondering how a well works or where does well water come from, then you’re in the right place. Well water is essentially groundwater water found underground in aquifers. Generally, aquifers contain sand, sandstone, fractured rock, and gravel, and water passes through the spaces between them. It eventually moves to the surface, ending up in springs, rivers, lakes, seas, and oceans.

Wells are basically holes drilled into the ground to access groundwater inside the aquifers. How deep a well goes is dependent on the depth of the aquifer. Using a pipe and pump, water will be drawn out and a filter is usually used to remove sediments and purify the water.

In this guide, you will learn more about wells and well water along with the necessary information that is relevant. Without further ado, let’s take a look at where well water comes from.

Where Does Well Water Come From?

As mentioned earlier, well water comes from underground aquifers, which are essentially underground layers of water-bearing permeable rock, fractures, or unconsolidated materials such as gravel, sand, or silt.

Water goes into an aquifer as precipitation seeps through the soil and surface again through natural springs and wells. A portion of the water in an aquifer will end up forming rivers and lakes or find its way to the seas and oceans.

How Deep Should A Drinking Water Well Be?

The depth of the aquifer will affect the depth of a well. However, the general rule of thumb is that your well should be at a minimum of 100 feet deep if you want the water that comes out of your faucets to be clean to use and drink. You should also note that a 100 feet depth is recommended to be the minimum because deeper wells usually provide cleaner and healthier water.

Deeper water usually contains various minerals and is less likely to be contaminated. But, it would still be wise to use a water filtration system for peace of mind before cooking or drinking the water. This ensures that any potential contaminants and impurities are removed.

Types of Well Water Systems

Before we take a look at how wells work, it is useful that you understand the three types of well water systems. Determining if your water is safe to drink without purification or not depends on the type of well you’re using. The three well water systems are namely dug or bored wells, driven wells, and drilled wells.

Dug/Bored Wells

Wells that are dug or bored are usually shallow wells and the reason that they are shallow is that they are opened with a shovel only. The depths of wells like these are usually 10 to 30 feet deep only and are cased with brick, tiles, stones, or other heavy materials to prevent collapse.

Since the water is very close to the surface, there’s a high chance that the water is contaminated. As such, it is highly recommended that you either boil or purify the water with a water filtration system before using or consuming it.

Driven Wells

This type of well is slightly deeper than the previous one but is still not deep enough that you get clean water. The depth ranges between 30 and 50 feet and this kind of well system is constructed by driving a pipe into the ground. It is also a good idea to purify the water that comes from these wells before you use or consume it.

Drilled Wells

The type of residential wells that provide the best depth is made with percussion or rotary drilling machines. Wells constructed from drilling are capable of reaching thousands of feet and require professional casing installation.

Due to the drilling process, they are typically quite costly to make, but the water that comes from drilled wells is normally clean enough that it doesn’t require any purification. Since the water also travels through multiple layers of soil to the aquifer, it will also be packed with healthy minerals and micronutrients.

How Do Wells Work For a House?

Water wells work in such a way that they collect groundwater and move it through your home’s plumbing system. To do so, the well will need to have multiple parts working together. The lowest section of the well will be the screen, then the well casing, and the last part of a well is the head.

Typically, the screen acts as a filter system to block out sediment and debris as water passes through it. After passing through the screen, the water will end up in the well casing. The well casing is essentially a length of pipe that ensures the underground water and your plumbing system remain connected.

The final part of a well is the head. It is basically the tip of the casing protruding out of the ground. The head acts as a point of access to let you sanitize the well water and it is usually covered with a cap to prevent contamination by pets or wildlife.

Most modern wells have the well casing equipped with a submersible pump, while older ones may use a ground pump, for the purpose of pushing the water up to the casing and into the distribution pipe of your home. It will then be connected to a pressure tank that provides for all the plumbing in your home. This ensures that your faucets and fixtures have sufficient water pressure.

Construction of a Well

Here are the parts involved in the construction of a well and all these parts operate together to provide a smooth system.

Well Screen

When a well pumps water from a sand or gravel aquifer, the screen will act as a sieve or a strainer to prevent sediment from entering the well. The screen sizes are depending on the size of the sand or gravel particles of the aquifer. A PVC screen is typically used and is usually 10 feet in length for residential wells.

A gravel pack or a filter pack may be located outside the well screen, between the screen and the bore hole wall for the purpose of keeping fine particles from entering and promoting the movement of water into the well.

Well Casing

Many new water wells are lined with PVC pipe which is essentially the well casing. The casing normally has a diameter of 4 to 6 inches and extends from above the ground surface into the aquifer. The casing also provides a connection to the groundwater and a path for bringing the water to the surface.

With a casing, loose soil, sediments, rocks, and contaminants are disallowed from entering the well. However, the casing must have a proper vent and a cap to prevent other contaminants from getting into the well.


The result of the drilling method is a bore hole that has a bigger diameter than the casing, which creates a space, known as an annular space, between the outside of the casing and the bore hole wall. To fill this annular space, a material called grout is used, which is a specific mixture of water and cement, or water and “bentonite” clay.

Grout is required to be pumped in from the bottom of the well and in an upward direction to ensure there is a complete seal around the casing. A grout pipe will be inserted down to the bottom of the space between the casing and the bore hole and the grout will then be pumped in until it reaches the ground surface.

After drilling, a well must be grouted from a required minimum depth to the surface. You should also take note that grout must not be poured into the annular space from the surface.

Well Water Advantages and Disadvantages

With a clearer understanding of how a well works, let’s take a look at some of the advantages and downsides of well water compared to city water.


  • Fresher and healthier water. Since well water comes from underground, it is naturally purer than city water, which is usually collected from the ground or shallow underground sources like lakes or rivers. While traveling through layers of sediments, the well water will be packed with healthy minerals such as calcium, magnesium, sodium, and other micronutrients.
  • Better taste. The naturally occurring minerals give the well water a better taste, while city water usually has an unpleasant taste due to the chemicals used to treat it.
  • No water bills. If you are getting water from a private well, you will save money on your utility bills.
  • Fairly low risk of contamination. In the event of natural disasters like floods, city water will normally be contaminated. Thankfully, your well water will not be affected, unless it was a horrendous disaster.
  • Limitless water source. City water is controlled by a municipality, so if a drought happens, most cities limit the city water supply. However, that will not be the case for well water because it is essentially endless. Even if water level decreases in your well during a terrible drought, you can still use as much water as you want to.


  • Depends on electricity. The pump responsible for bringing water from the well into your home requires electricity. As a result, your water supply will be cut off in the event of a power outage. If you reside in an area that has the tendency to experience power blackouts, it would be wise to invest in a power generator.
  • Need to be responsible for your water quality. While well water is generally clean enough to consume, it is still your responsibility to have the water tested and make sure that it is free of harmful contaminants. Besides being responsible for the water quality, you will have to be responsible for any well-maintenance works too.
  • Most well water is hard water. While the things found in well water are good for your health, they can actually be troublesome. The most common issue you will face with using well water is limescale deposits on your plumbing. These build-ups can potentially cause damage to your dishwasher or washing machine. Excessive consumption of any mineral can also lead to serious health issues.

Well Pumping Systems

A water system is required in order to pump water out of the well. Generally, a home water system will contain a pump, a pitless adapter or unit, and a pressure tank along with control devices for it to operate automatically.


The two common pumps are submersible pumps and jet pumps. A submersible pump is the most common choice and usually comes with a pump and a motor unit. On the other hand, jet pumps are more commonly used for a well with 4 inches or less in diameter. Jet pumps work by forcing water through a jet or venturi, and draws water from the well into the pumping system.

Pressure Tanks

As the name suggests, a pressure tank holds water under pressure. When you open a faucet, the air pressure in the tank will force the water through your pipes to a point where the pressure drops to another preset level, where it will start pumping again. The size of a pressure tank can range from 10 gallons to well over 200 gallons.


There are many advantages when it comes to using well water, but there are also responsibilities to be taken into account too. With a better understanding of how a well works, you can now make more informed decisions on whether you want to use well water or not.


How many years do water wells last?

Generally, water wells last between 25 and 100 years. However, it depends on where you live because the more precipitation in your area, the longer the well will last. After many years of use, more drilling could be required.

Where is the ideal well location?

Ideally, a well should be located far away from utilities, buildings, and other contaminants. The best location is usually identified by considering where the existing buildings, septic systems, buried gas or power lines are located at.

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