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Home » Water Education & Testing » How Deep Should a Well Be for Drinking Water

How Deep Should a Well Be for Drinking Water

By: Craig Smith
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If you are getting ready to put a well in at your home, you should be aware that there is much more that’s involved in that process than just digging down into the ground. 

The most important factor when drilling a new well is the depth that it will be dug at.

There is actually a list of items that I have put together that will better acquaint you with how the depth of your new well will be determined.

Once you learn what to consider when deciding how deep should a well be for drinking water, then you will be able to better plan for the project along with the company that’s doing that job for you. 

This is also good to know before you start digging your well because most drilling companies charge by the foot. 

There can be a pretty substantial cost difference between a well that’s 150 feet deep and a well that’s 300 feet deep.

What Determines How Deep a Well Should Be?

Although most wells across the country range from 100 to 500 feet in depth, some go as many as 1000 feet into the ground. Here are some of the reasons for the depth discrepancy between different wells.         

Depth of Aquifer

It’s probably stating the obvious here but it does not matter how far down a well is dug if it doesn’t reach a water source. This is one of the biggest reasons for the difference in well depths in different areas of the country. 

Even aquifer supply systems in neighboring counties can be found to be at many different depths.

Risk of Surface Contamination

The closer your well is to the ground surface above it, the higher the risk that harmful contaminants will be found in your well water. This is because the water that started at the surface has not gone through as many rock, sand, and gravel layers that will naturally filter it.

So, this is always a major consideration if you are in an area that has such characteristics as nearby farmlands. 

In these areas pesticides, herbicides, and bacteria from animal waste are known to constantly find their way into the shallower aquifers. 

That means you will want to drill your well deeper in these types of situations.

Geology of Bedrock

Various types of rock layers lay beneath the earth’s surface. What role do they play in the determination of your well’s depth? Let’s just say that there are some types of bedrock that a drilling company is more willing to drive a well through than others.

Sedimentary rock layers made up of limestone and travertine are fairly easy for a good well drilling rig to punch through. That’s hardly the case for tougher metamorphic rock layers made up of such rocks as quartz and marble.

So even though you like the quality of the water from your neighbor’s well which goes down 300 feet, your well’s depth might not be able to go down that far if your home is located over bedrock that is made up of a tougher type of stone to drill through.

Water Quality

You may hit water as soon as 100 feet down when drilling your well but what if the water quality at that depth is not very good? This is a common situation for shallower wells. As a general rule of thumb, the deeper you drill a well the higher your water quality will be.    

That’s also why it’s good to choose a well-digging company that has much experience in your area. They will usually be familiar with how deep wells in the area need to be drilled to reach higher quality drinking water.   

Fluctuations of Water Table

When considering what well depth to drill to, you also have to take into account water table fluctuations. Many of these relate to seasonal patterns such as rainy seasons, dry seasons, and snowmelt seasons. 

If you drill your well at the time of year with the highest rainfall, it may not have enough water in it to meet your needs during the dry season.

Droughts will also impact aquifer water levels. It may even be the case where too many high-use wells obtain their water from the same aquifer and lower the water table in that aquifer.


Most states also have well-digging regulations or at least have guidelines in place. The company digging your well should be very familiar with these. They better be because most states also require well-digging companies to be registered and approved.

It will never hurt you to become familiar with the regulations that are necessary to drill a well in your area before you start your project either. That’s because you are most likely going to be required to take out a permit for the job and that comes with some responsibility.

So How Deep Should Your Well Be For The Best Drinking Water?

As you have noticed when reading, it is very hard to predict the level that your new well will end up being. There just is a lot to consider and a lot of unknowns that can be encountered during any well digging process.

If you really want an answer to the question ‘how deep does my well need to be’, then the best place to find that answer is by asking a local company that digs wells. 

They can tell you at what depths the wells in your area need to be drilled to in order to obtain decent quality drinking water.  

No matter what depth your new well ends up being, I will provide you with one last bit of advice. That has to do with the fact that there is no well on the planet that is 100% free of impurities.

This includes the possibility of having bacteria, arsenic, lead, and other harmful contaminants in it.

That’s why after your new well has been dug, you should strongly consider adding a well water treatment system onto your main or kitchen sink water line. 

This will ensure that you and your family have access to healthier drinking water in your home. 

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Craig Smith
Craig got his start in water working in the swimming pool and spa industry. Water treatment would grow into his main career but he ended up working in the pool industry for over 26 years where much of his time was spent balancing the water in customer's swimming pools and installing water filtration equipment. Craig offers an abundance of water treatment knowledge after helping homeowners get pure water for 26 years.

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