A private well is a water supply system owned and maintained by an individual homeowner or property owner, drawing groundwater from beneath the land rather than receiving treated water from a city or municipal utility. More than 23 million households in the United States rely on private wells for their drinking water. Unlike public water systems, private wells are not regulated by the federal government under the Safe Drinking Water Act, which means the homeowner is fully responsible for ensuring the water is safe to drink.
How a Private Well Works
A private well taps into groundwater stored in underground rock formations and soil layers called aquifers. A pump, usually installed deep inside the well, pushes water up through a pipe and into your home’s plumbing system. The well is lined with a casing, typically made of steel or PVC, that prevents the surrounding earth from collapsing into the hole and helps keep surface contaminants from seeping into the water supply.
During construction, the space between the casing and the drilled hole is sealed with a grout material to block pollutants from traveling down the outside of the casing. At the surface, a well cap covers the top to keep out insects, debris, and rainwater. The system relies on electricity to run the pump, which means water stops flowing during a power outage. A power loss can also cause the system to lose pressure, potentially allowing contaminants into the plumbing.
Three Main Types of Private Wells
Not all wells are built the same way. The type you have (or need) depends on your local geology and how deep the groundwater sits.
- Dug or bored wells are the simplest and shallowest type, typically 10 to 30 feet deep. They’re created with a shovel or backhoe and lined with stone, brick, or tile. Because they’re shallow and not continuously cased, they’re the most vulnerable to surface contamination.
- Driven wells are built by driving a narrow pipe directly into the ground, reaching depths of about 30 to 50 feet. They’re continuously cased, which offers somewhat better protection than dug wells, but they still draw from shallow groundwater.
- Drilled wells are the most common modern option. Constructed with rotary or percussion drilling machines, they can reach hundreds or even thousands of feet deep. The greater depth generally means better protection from surface pollutants and a more reliable water supply. Drilled wells require full casing installation.
Private Wells vs. City Water
The biggest difference is oversight. City water is treated with disinfectants, tested regularly by government officials, and held to federal drinking water standards. With a private well, none of that applies. You’re the one testing, treating, and maintaining the system.
The tradeoff is cost and independence. Well water itself is free once the system is installed. There’s no monthly water bill. A properly built well can last decades, and it can be constructed in nearly any environment where local laws permit. For rural properties without access to municipal water lines, a private well may be the only practical option.
On the other hand, well water often contains higher levels of dissolved minerals that make it “hard,” leading to scale buildup in pipes and appliances. It can also carry naturally occurring contaminants like arsenic, which is more commonly found in drilled wells than in municipal sources. Fertilizer runoff and failing septic systems nearby can introduce nitrates and bacteria into groundwater. Because no utility is monitoring these risks for you, they can go undetected without regular testing.
What It Costs to Drill a Well
As of 2025, residential well drilling typically costs $25 to $65 per foot, including the casing. A relatively shallow well of 100 to 200 feet might run a few thousand dollars, but deeper wells in the 600 to 800 foot range can exceed $15,000 to $50,000 before adding pumps, storage tanks, or water treatment equipment. The final price depends heavily on your local geology, since harder rock and greater depth both increase drilling time and cost.
After installation, the ongoing expenses are maintenance and occasional repairs. There’s no monthly water bill, but you’re responsible for every component in the system.
How Long the System Lasts
A well isn’t a single piece of equipment. It’s a collection of components with different lifespans. The well itself, meaning the drilled hole and the aquifer it draws from, can last 30 to 50 years or longer with proper maintenance and stable aquifer conditions. The steel or PVC casing typically holds up for 20 to 50 years, depending on the material and how corrosive the surrounding soil and water are.
The pump is the part you’ll replace most often. Most well pumps last 8 to 15 years. Submersible pumps, which sit deep inside the well, generally outlast jet pumps that are installed above ground. Usage patterns and water quality both affect how quickly a pump wears out. High sediment or mineral content in the water accelerates wear on moving parts.
Testing Your Water
The CDC recommends testing your well water at least once a year for four things: total coliform bacteria, nitrates, total dissolved solids, and pH level. Coliform bacteria indicate whether disease-causing organisms may be present. Nitrates are especially dangerous for infants and can enter groundwater from agricultural runoff or septic systems. Your local health department may recommend additional tests based on contaminants common in your area.
Beyond the annual water test, you should inspect the well itself every spring for mechanical problems. Look for cracks in the well cap, signs of settling around the wellhead, and any changes in water taste, color, or odor. After flooding, heavy construction nearby, or any event that disturbs the ground around your property, test again even if you’re not due for your annual check.
Protecting Your Well From Contamination
Where your well sits on the property matters. Ideally, it should be on higher ground so that surface water naturally drains away from the wellhead rather than toward it. If the well is in a flood-prone area, the casing should extend at least 2 feet above the highest recorded flood level. The well should also be uphill from any areas where pesticides, fertilizers, or animal waste might be present in runoff.
Everyday habits around your property affect your water quality too. Never dump motor oil on the ground. Don’t flush medications down the toilet, since they can reach groundwater through septic systems. Install vacuum breakers on outdoor faucets to prevent water from being siphoned back into your plumbing if a hose is submerged in contaminated liquid. And if your property has an old, abandoned well, never use it for garbage disposal. Abandoned wells that aren’t properly sealed act as direct pipelines for surface pollutants to reach the aquifer.
Backup Power for Well Owners
Because private wells depend on an electric pump, losing power means losing water. This is one of the most practical differences between well water and city water that new well owners don’t always anticipate. You can’t flush toilets, run faucets, or use appliances that need water until power is restored.
A portable or standby generator sized to handle your well pump is the most common backup solution. Some homeowners also keep a supply of stored water on hand for shorter outages. Beyond the inconvenience of no water, there’s a safety concern: when the system loses pressure during an outage, contaminants can potentially enter the plumbing. After power is restored, it’s a good practice to run the water for several minutes before drinking it, and to test it if the outage was prolonged or coincided with flooding.