Deep Well vs. Shallow Well: What’s the Difference and Why It Matters for Homeowners
Bring depth differences to the surface
Highlights
Shallow wells have an average depth of under 50 feet.
Most deep wells are between 100 and 1,000 feet deep.
Deep wells have better filtration but may have higher mineral and radioactive elements.
Shallow wells are cheaper to dig and maintain.
Deep wells generally withstand drought better with a more consistent water source.
It may seem like deeper is better when it comes to wells, but several factors go into deciding between a deep well vs. a shallow well for your home. Both can provide a self-reliant source of water for your family, but each has advantages and disadvantages. The difference in average well depth between deep wells and shallow wells can affect reliability, water quality, budget, and more. Take all of these characteristics into account when choosing the right well for your property.
Summary of Differences Between Shallow and Deep Wells
Listed below are some of the key differences between deep wells and shallow wells. The average well depth for each type is the most obvious. Depending on how deep you dig, this can impact the typical characteristics of the water that your well pump can provide.
| Characteristic | Shallow Well | Deep Well |
|---|---|---|
| Depth | 25 – 50 feet | 100 – 1,000 feet |
| Casing Diameter | Usually 1 1/4-inch | Over 2 inches |
| Hard Water | Less likely | More likely |
| Radioactivity | Less likely | More likely |
| Contamination | More likely | Less likely |
| Pump Location | Above ground | Submersible |
| Drought Risk | Higher | Lower |
| Average Cost | $1,500 – $2,500 | Up to $25,000 |
Average Well Depth
If you are going to dig a well by hand, it’s going to be a shallow well. The average well depth for a shallow well is between 25 and 50 feet. This depends on what the water table looks like on your property, something a professional driller can help assess for you. It’s important to consider groundwater conditions in different seasons if you want a year-round source of water.
By contrast, the average well depth for a deep well is at least 100 feet and can be as deep as 1,000 feet. Most deep wells fall into the 100 to 500 feet range. One reason to consider this greater well depth is the lack of a reliable water source closer to the surface on your property.
Casing Diameter
Another characteristic that separates deep wells vs. shallow wells is the diameter of the casing. A shallow well point will typically use 1 1/4-inch PVC piping for its casing. In some cases, shallow wells can also have wider diameters. Bored wells are very shallow, but may have a casing diameter of around four inches.
By comparison, deep wells often use casing that is at least two inches in diameter. The larger diameter helps to improve water flow.
Hard Water Components
Well depth directly impacts water quality. Remember what well water is in the first place: It’s groundwater found in underground aquifers. This water has not been treated or filtered in any sort of artificial way—it’s literally surrounded by nature. Depending on the geography of your area, deep wells typically contain more hard water components than shallow wells.
This can include naturally occurring elements like calcium, magnesium, iron, and manganese. The higher mineral content doesn’t necessarily mean the hard water is not potable. But, you can address this concern by installing a water softener as part of your well water system. Shallower well depth usually offers fewer hard water components.
Radioactive Elements
The deeper the well, the closer you are to the Earth’s core. A natural side effect of this is that deeper wells may have higher levels of radioactivity compared to shallow wells. This is heavily dependent on your local geology. Water well professionals in your area can provide greater insight into possible radioactive elements in your water.
Surface Contaminants
While deeper well depth may have higher radioactive elements and hard water components, it will also have fewer surface contaminants. The deeper the well, the more it can benefit from the natural filtering that the many layers of soil provide. Bacteria trapped well below the surface in rock and sediment can’t survive down there for long.
Shallower well depth, on the other hand, is much more susceptible to surface contamination. Content from fertilized fields, farm animals, wildlife, septic systems, human activities, and other land uses can all contaminate shallow well water. When choosing a location for DIY well drilling, stay as far away from these sources of contamination as possible. Inspect, test, and treat shallow well water frequently.
Pump Type and Location
Whether you have a shallow well or a deep well impacts the type and location of the well pump you will have, too. Shallow wells will have a pump that is above ground, which allows for easier well maintenance but is obviously visible.
Deep wells often have a submersible well pump that could be several hundred feet deep. This may be more aesthetically pleasing, but it can make servicing and maintenance more work-intensive. You may not need to know how to prime a deep well pump after installation as they are often self-priming. The larger diameter of deeper wells improves flow and provides room for a submersible pump.
Susceptibility to Drought
Deep wells are less at risk of drying up than shallow wells. The increased well depth taps into a more consistent source of water that’s less affected by surface conditions. Shallow wells can be susceptible to drought, especially in deserts and more arid regions.
During dry spells, the water table can lower beyond the reach of a shallow well. This can keep dropping over several years until the shallow well can’t reach the groundwater at all. Consult with well pump contractors near you who have intimate knowledge of local conditions. They can recommend an acceptable well depth for you.
Average Cost
One of the biggest factors separating deep wells and shallow wells is cost. This includes both well drilling costs and ongoing maintenance and repair costs. The deeper and wider the well is, the more it is going to cost. Construction calls for heavier equipment, more materials, and much more labor. This initial investment may be worth it in areas with more surface contamination or lower water tables.
Frequently Asked Questions
Depending on local conditions, a deep well may be a better choice than a shallow well. Deeper well depth accesses groundwater that has been naturally filtered through many layers of soil and rock. This reduces surface contaminants and may offer cleaner water, but deep wells cost more money to build and maintain. The water may be harder and have higher radioactivity, too.
Most deep wells can be expected to last somewhere between 30 and 50 years. This assumes that the well and all of its components are properly maintained on a regular basis. During this time, it is unlikely that modern deep wells will run dry over the course of their typical lifespan. That is one of the biggest benefits of digging a deeper well.
Most shallow residential wells are somewhere between 25 and 50 feet deep. They are among the simplest well systems. Deeper wells usually involve drilling to a much greater depth. Water wells for household use are typically 100 to 500 feet deep, depending on local groundwater conditions. Some may be up to 1,000 feet deep or more.