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How Deep Should a Well Be for Drinking Water?

Owning a private well lets, you save money on water bills. However, if you are considering constructing a new well or replacing an existing one, you must ensure that your water source is drinkable. 

A well for drinking water should be deep enough to access the body of rocks or sediments that holds water, known as the aquifer. Therefore, the well should be at least 100 feet underground or deeper. 

But the well’s depth is just one part of the equation. This article will go through the different factors homeowners must consider when constructing wells. 

What Is a Well, And Why Are They Important?

What Is a Well, And Why Are They Important?

A well is a shaft that is either dug, driven, or drilled into the ground to draw water. 

Everywhere across the planet, wells have provided various communities with clean water for centuries. According to recent data, an estimated 42 million people use wells as their water source in the United States alone. This number accounts for 13% of the population.

Several industries, farms, and households rely on wells for water supply. Wells are also helpful for communities in areas not connected to centralized systems or where surface water may be limited.

How Deep Should a Well Be For Drinking Water?

To ensure that your well provides clean drinking water, it should be at least 100 feet deep. 

The well’s average depth for most private homes is between 100 to 1000 feet. This should be enough to prevent surface contaminants from entering the well. 

Factors Affecting How Deep a Residential Water Well Needs to Be

Factors Affecting How Deep a Residential Water Well Needs to Be

Depth Of Water Table

As mentioned earlier, wells obtain water from aquifers located underground. However, let me also add that the actual depth varies from one location to another. 

Case in point: The Oglalla Aquifer. It spans over 174,000 square miles covering portions of the United States eight states.

Oglalla Aquifer’s water table varies from 50 to 300 feet below the land surface, meaning some folks will have to drill deeper to reach the reservoir.

If you want to know the depth of the water table in your location, you can use tape to measure the water level in a shallow well. 

Alternatively, I recommend checking your state government’s drillers’ logs or the United States Geological Survey’s website.


Surface water is more prone to contamination. Again, depending on where you live, this could be animal wastes, fertilizers, or motor oils.

To avoid this, drillers typically increase the length of the casing and the depth of the well. As a result, the water can take more time to flow from the aquifer to the pump. 

If the water spends more time in the subsurface, the bacteria will likely get stuck in the soil and rocks or die off. 

Fluctuation of the water table

The idea of having a private well at home sounds appealing. After all, it is often touted as having unlimited access to drinking water. But this will not happen if your well is not deep enough to draw water when the water table drops. 

The water table will fluctuate throughout the year due to seasonal precipitations or droughts. Therefore, your well needs to extend below the water table to ensure you don’t run out of water. 

Regulations on well location and construction

Regulations on well location and construction

The government regulates both the location and the construction of wells. 

Whether you are hiring a driller or doing the digging yourself, the well must meet the standards detailed in the installation code. 

Each state may have different rules, but generally, you must ensure that your well is located far away from contamination sources. The state also recommends specific materials and construction techniques appropriate to specific environments.

Geological features

The total depth and diameter of the well are determined based on the geological features of where you intend to build a well. 

Typically, low-yielding rock formations will work best with wells that are deeper and larger in diameter. As such, the well not only obtains water but also functions as a storage cavity for groundwater. 

Poor water quality

Some areas in the US with multiple aquifers may have been cased off due to poor water quality

In these cased-off zones, drilling is restricted to prevent the lower-quality water from getting into your well. You can consult with the local drilling company and government to learn more about the water quality in the area to come up with possible solutions.

People Also Ask

Do deeper wells mean better water?

Do deeper wells mean better water?

Many homeowners equate deeper wells with better water quality, but this is not always the case.

The water in the deeper parts of the well has been there longer. As a result, they contain naturally occurring contaminants. In addition, calcium and magnesium, the minerals that form hard water, are abundant deeper in the aquifer.  

However, one advantage of having a deeper well is that some contaminants can have more time to break down. Therefore, its quality substantially changes when the water reaches your deep well. 

Are shallow wells good?

It depends. Shallow wells can work if you live in a non-agricultural area and have complete control over the land use so that no pollutant will contaminate your water source.

Still, the construction of the well must meet the minimum depth set by your local state.  

Is 300 ft a deep well?

It would help if you considered not the entire length of the well but how far the casing dips into the water table. 

For instance, you have two wells 300 feet deep built in two parts of the country. One well is made in a region where the water table is located 250 feet. 

Meanwhile, the other well is constructed with a water table around 100 feet below the land. 

The latter is considered “deeper” between the two because a huge fraction of its casing reaches deeper into the water table.


Determining how deep you well should ideally be is not a straightforward process, as it turns out; how shallow or deep a well is entirely subjective when you factor in the depth of the water table in your location.

Moreover, you should also consider the quality of your area’s groundwater, local regulations, geological conditions, and potential contaminants. But once you successfully install your well, you can enjoy an endless drinking water supply. 

Remember that owning a private well means getting your water regularly tested to ensure it is free of bacteria.

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