A shallow well is generally any well less than 50 feet deep, though the exact cutoff varies by state and construction method. These wells tap into groundwater close to the surface, making them cheaper and easier to build than deep wells but more vulnerable to contamination and drought. Understanding the distinction matters because it affects everything from the type of pump you need to how often you should test your water.
How Depth Defines a Shallow Well
There is no single federally mandated depth that separates “shallow” from “deep,” but the EPA describes the two most common shallow well types as reaching no more than 50 feet. Dug or bored wells, the simplest kind, are typically 10 to 30 feet deep. Driven wells, built by hammering pipe into the ground, reach roughly 30 to 50 feet. Anything constructed with a rotary or percussion drilling rig can go much deeper, sometimes thousands of feet, and is classified as a drilled well.
For context, USGS data shows that the median depth of domestic drinking water wells across the United States is 142 feet, and for public supply wells it’s 202 feet. So a well in the 10 to 50 foot range is drawing from a much shallower zone than most of the country’s water supply infrastructure.
Where Shallow Well Water Comes From
Shallow wells draw from what hydrogeologists call an unconfined aquifer, also known as a water table aquifer. This is the uppermost layer of saturated ground, where water fills the spaces between soil, sand, and gravel. There is no impermeable rock layer sealing it from the surface, so the water level rises and falls freely with rainfall, snowmelt, and seasonal changes.
Deep wells, by contrast, often reach confined aquifers. These are underground water sources sandwiched between layers of dense rock or clay. The confining layers act like a cap, keeping the water under pressure and largely shielding it from what happens at the surface. That pressure is also why some deep wells produce water that rises on its own once the drill breaks through.
Because shallow wells sit in unconfined aquifers with a direct connection to the surface, they recharge faster after rain but are also the first to feel the effects of drought or heavy pumping nearby.
Construction Methods
The three main types of shallow wells differ in how they’re built and how wide they are:
- Dug or bored wells are excavated with a shovel or backhoe and lined with stone, brick, or tile to prevent the walls from caving in. They have a large diameter but are the shallowest option, usually 10 to 30 feet. Because the casing is not continuous, gaps between lining materials can let surface water seep in.
- Driven wells are made by hammering a small-diameter pipe with a screened tip directly into soft ground. They reach 30 to 50 feet and have continuous casing, which offers somewhat better protection against surface contamination than dug wells.
- Drilled wells can be shallow or deep depending on the geology, but once you need a drilling rig, the well is usually taken deeper than 50 feet to reach more reliable water.
Why Pump Type Depends on Depth
One of the most practical reasons the shallow vs. deep distinction matters is pump selection. A standard above-ground pump works by creating suction to pull water up from the well. Physics limits how far suction alone can lift water: the reliable maximum is about 25 feet from the water surface to the pump inlet. In practice, that number can be even lower if the piping between the well and pump is long or narrow, which increases friction losses.
If your water level sits within that 25-foot suction range, a simple shallow well jet pump mounted on the surface will work. Once the water drops below that threshold, you need either a deep well jet pump (which uses a special fitting installed down in the well to boost pressure) or a submersible pump placed entirely underwater inside the well casing. Submersible pumps require a well diameter of at least 4 inches.
This means a shallow well’s usable depth is partly defined by the equipment it can support. Even a 40-foot well can function as a “shallow” system if the water table sits high enough for a surface pump to reach it.
Contamination Risks
Shallow wells face greater contamination risk than deep wells because they draw from water that is closer to the surface and less filtered by layers of earth and rock. The EPA identifies several categories of contaminants that are especially concerning for shallow well owners.
Microorganisms like bacteria, viruses, and parasites can enter a well through rainfall runoff, snowmelt, leaking septic systems, or underground storage tank failures. These organisms are naturally present in human sewage and animal waste, and drinking contaminated water can cause gastrointestinal illness and infections. Dug wells with non-continuous casing are particularly susceptible because surface water can seep directly through gaps in the lining.
Nitrate is another major concern. It comes from chemical fertilizers, animal waste, and septic effluent, and it moves easily through soil into shallow groundwater. Nitrate is especially dangerous for infants under six months. At high levels it interferes with the blood’s ability to carry oxygen, a condition sometimes called “blue baby syndrome” that can develop rapidly over a matter of days. Symptoms include shortness of breath and bluish skin.
Pesticides, heavy metals, and volatile organic compounds from nearby industrial or agricultural activity can also reach shallow groundwater more readily than deep, confined sources.
Testing and Maintenance
Private wells, including shallow ones, are not regulated by the federal Safe Drinking Water Act. Most state governments don’t regulate them either. That puts the responsibility for water quality squarely on the well owner.
The CDC recommends testing your well water at least once a year for total coliform bacteria, nitrates, total dissolved solids, and pH. Nitrate testing every year is considered especially important given the health risks to infants. If your area has known issues with specific contaminants like arsenic, radon, or pesticides, add those to your annual panel.
Beyond water quality testing, inspect the physical well structure every spring. Look for cracks in the casing, damaged well caps, and signs of settling or erosion around the wellhead. A dug well with deteriorating lining material is an open invitation for surface contaminants. Keeping the area around the well graded so that rainwater flows away from it, rather than pooling near the opening, is one of the simplest things you can do to protect your water.
Drought Vulnerability
Shallow wells are significantly more affected by drought than deep wells. Because they tap into the water table aquifer, which responds directly to rainfall patterns, even a few weeks of below-normal precipitation can cause the water level to drop. During prolonged drought, the water table may fall below the well’s pump intake, effectively causing the well to go dry.
USGS data confirms that wells screened in unconfined water table aquifers are more directly influenced by lack of rain than those reaching deeper confined aquifers. Heavy pumping compounds the problem. If you draw water faster than rainfall can recharge the aquifer around your well, levels will continue to fall. This is a real concern in areas where multiple neighboring properties share the same shallow aquifer, or where irrigation demands spike during dry summer months.
Seasonal fluctuations also matter even in non-drought years. A shallow well that performs fine in spring may struggle in late summer when the water table is naturally at its lowest. If you’re considering installing a shallow well, knowing the seasonal range of the local water table is critical to choosing the right depth and pump setup.