More than 40 million Americans depend on private wells for their water. If you’re one of them, you may not fully appreciate how these modern miracles work.
A hundred years ago, it took an hour to draw a day’s supply of water from a hole in the ground with buckets. It’s no wonder our grandmothers were exhausted.
But modern wells draw water out of the ground automatically and supply water on demand. Yet how long has it been since we’ve given them a round of applause?
If it’s been a while since you’ve given your well a second thought, join us as we explore the basics of residential wells and answer common questions from how does a well work to what to do if your pressure tank or water pump fails.
Let’s start with the basics.
What Is a Well?
A well is vertical hole in the ground equipped with an automated pumping system. There’s nothing mysterious about it. It’s that simple.
Where Does Well Water Come From?
Surface water wells are very rare. Most well water comes from underground. As rainwater and melted snow seep through the soil, they feed the underground rivers and aquifers typically tapped for well water.
How Does a Well Work?
Wells consist of three major parts — the well, the pump and the water pressure tank.
The well pump is sunk into the soil just below the water table — the level at which the ground is saturated. It then water into a pressure tank that then feeds your home.
Let’s take a closer look at the different types of wells and their components.
Types of Wells
Where there’s a will, there’s a way. There are unusual types of well water systems from gravity-fed wells that get water from a storage tank to artesian wells that don’t require pumps. But most modern wells are one of these common types:
1. Drilled Wells
Drilled wells access water contained hundreds of feet below the earth’s surface. It takes rotary drilling machines to bore the holes. Lined with a well casing to keep it from collapsing, a drilled well can last a lifetime if properly maintained.
2. Dug Wells
Dug, or bored wells, are shallow wells that draw water from the saturated zone — soil in which all the empty spaces are filled with water. The average depth varies based on how high or low the water table is — 30 feet is average. Most Americans get their well water from dug wells.
3. Driven Wells
Driven well water systems are a happy medium. Little more than pipes driven into the ground, they’re deeper than dug wells but shallower than drilled wells.
Type of Well Water Pumps
Every well water system depends on one of these types of pumps to get water from the ground.
Submersible pumps sit deep inside a well. Sealed to protect the electronic components, they rely on an impeller to push water upward.
Jet pumps are installed above ground. Unlike a submersible pump, they use centrifugal force to pull water from the well. It’s an important distinction to make because among well water pumps, they have the least horsepower. Most shallow well pumps are jet pumps.
Other Well Components
Each of these components complements the well pump and plays a vital role in your well system.
The well casing is the solid tubular structure through which well water is drawn. Made of steel or PVC pipe, it creates a permanent separation between your well water and the surrounding soil. Casings are treated with a concrete or clay sealant that helps keeps out the most common well water contaminants.
A water pump draws water out of a well and into a pressure tank. Why a pressure tank and not directly into your plumbing system?
Because water pressure decreases by half a pound per square inch for each foot your plumbing rises above ground level, so pressure tanks are necessary to propel well water to the second floor of your home. Without them, showers would be little more than a trickle.
As water from the surrounding aquifer fills the space at the bottom of the well, it brings dirt and silt with it. Well screens cover the bottom of the casing to keep sediment out of your water.
Is Well Water Better Than City Water?
Well water is synonymous with purity, but city water systems have advantages. Treated at the source, there’s a lower risk of bacterial contamination from city water, and the water pressure is better without the need for pressure tanks.
But unless you use a home chlorinator, only well water is free of disinfectants and their carcinogenic byproducts. Dozens of American water districts regularly have higher-than-legal limits of trihalomethanes and bromide, compounds created as chlorine breaks down.
A well water system, however, is vulnerable to other contaminants.
How Does Well Water Get Contaminated?
A well water system is fed by surface water that may contain harmful contaminants from motor oil to chemical fertilizers and other toxic materials. Any hazardous substance produced within your watershed — the area around your home through which water naturally flows — can end up in your well.
A properly constructed well is safe, but if contaminated ground water from a surrounding aquifer seeps into a cracked well casing, it can affect your entire well system.
What Are the Signs of Poor Well Water Quality?
The most common sign of poor water quality is water that smells, tastes or looks bad. And if your family has frequent bouts of gastroenteritis, coliform bacteria in your well could be to blame.
The EPA estimates that millions of Americans are drinking from contaminated wells, but don’t panic. Most issues can be fixed with a home filtration system.
Unfortunately, some of the most dangerous contaminants, however, like lead, arsenic and bacteria, have no flavor, color or odor, so the only way to know what’s in your well water is to test it.
The CDC recommends an annual test for nitrates and bacterial contamination plus occasional testing for contaminants common in your geographical area. The good news is — the testing process is a breeze.
Testing Well Water
Unlike city water, private well owners are responsible for their water quality. No government agency monitors or tests wells. It’s all up to you.
But testing is simple these days. Just bring a water sample to a local certified drinking water laboratory or purchase a DIY home water test kit online — see our top rated water testing kits. Products like SimpleLab’s Tap Score are a good solution for homeowners who want independent advice on choosing well water filtration products.
How Can I Keep Contaminants Out of My Well Water?
You can keep contaminants out of your well water supply with just a few simple steps.
If you’re installing a new well, avoid placing it at a low point on your property. Rain and melting snow can carry hazardous chemicals downhill into private wells.
You should also drill wells away from your septic system and underground fuel tanks. Ask a representative from your local health department to collaborate with your well contractor. They know which contaminants are the most common in your watershed and where they come from.
For existing wells, hire a contractor to inspect your well system periodically. No water filter will make your water safe if the pump or well casing is damaged.
Can A Well Run Out of Water?
In drought conditions, shallow wells can run out of water if the saturated zone dries up. What are the signs?
If you experience sudden water pressure drops, check your pressure tank and water pump first, but you could be running low. And if you get mud from your tap, your supply may have dropped below the water intake depth of your pump.
As long as the well itself extends past the top of the water table, a good round of rain may replenish the underground layers of soil surrounding your home and restore flow.
But if it doesn’t produce enough volume to create water pressure, or it dries up permanently, it’s time to call a well contractor. The only option is to drill a new one.
For more insight on this subject, read: How deep should my well be.
What Does a New Well Cost?
The average cost of a new well water system, from testing the ground and having the hole drilled to installing a well pump and pressure tank, ranges from $2000—$20,000 or more depending on the well depth. If you’re replacing an existing well and can salvage the water pressure tank or well pump, projects range significantly less.
The deeper you need to go, the more wells costs. But deeper wells are less likely to run dry. The quality of your private well system not only guarantees the integrity of your well water supply, but it adds to your home’s resale value. We recommend being investment-minded, beginning with choosing the best well contractor.
You could thumb through your local telephone directory, but we suggest contacting the National Ground Water Association. Experts in well water systems, their website is packed with helpful information and a link to WellOwner.org. They can connect you with a certified well water contractor.
How Do I Clear Dirty Well Water?
Dirty well water can originate from anywhere in your system. Pressure tanks, for example, can accumulate sediment over time and may require cleaning. But if you had your water tested, and it contains heavy metals or chemical contaminants, installing a water filter is the best solution.
An undersink or countertop unit may be all you need to purify drinking water, but you’ll need a whole-house water filter for wells to clean up bathing water.
How does a well work with a whole-home filtration system? It’s no different than with city water. It hooks into your plumbing system near the pressure tank and provides clean well water home wide.
If you own one of the twenty percent of homes that rely on well water, it pays to maintain your well system. Take good care of it and it will take good care of you.