Is Well Water Safe to Drink?

Reviewed by: James Layton
Updated on:
March 6, 2024

Key Takeaways

  • All wells are different so please consider getting your water tested by Tap Score to verify your water quality before drinking it.

What Makes Well Water Safe?

As long as you monitor your well’s water quality and install appropriate filtration, if needed, well water is safe to drink!

In fact, almost 140 million people in the US pump groundwater into their homes for daily household use.

Investing in a healthy private well pays off in terms of taste, health, cost, and property value, but it requires regular maintenance.

Top of the list is testing.

You need to have your well water tested annually because well owners are responsible for their own well water quality, unlike those hooked up to municipal water, which is treated by the local government and monitored by state and federal authorities.

Based on the results of your water analysis, you may need to install a well water filtration system that tackles whatever impurities showed up in the water report.

Before you buy one, consult this list of the best water filtration systems for well water.

If you don’t want to invest in a treatment system, you’re better off with a property connected to the municipal water supply.

However, while municipally treated water is safe to drink, it might include treatment chemicals that some people don’t appreciate.

Having a private well means you’re in charge of what’s in the well water. If that appeals to you, keep reading to find out more about keeping your well water safe.

Common Well Water Contaminants

You will never delay your well water inspection once you learn about the damage these contaminants can do to your body.

This section explores health concerns associated with the most common contaminants in well water, including naturally occurring chemicals, and how to remove them.

(Psst: For information about water filtration systems and other treatments, you can find details on well water purification methods and techniques here.)

Sulfur and hydrogen sulfide

Hydrogen sulfide occurs naturally in groundwater, especially in areas with high concentrations of organic material or minerals containing sulfur, such as pyrite.

When bacteria break down organic matter in the absence of oxygen, they produce hydrogen sulfide as a by-product. This process commonly occurs in deep wells or aquifers where the water has been stagnant for some time.

The hydrogen sulfide gas dissolved in the water can then give off a distinct rotten egg or sulfur smell.


Consuming well water contaminated by total coliform bacteria, viruses, and parasites can cause stomachache, nausea, vomiting, diarrhea, jaundice, and other gastrointestinal illnesses.

In fact, such microorganisms are the leading cause of most waterborne diseases around the world.

These harmful contaminants usually come from organic waste, such as human sewage or animal feces.


First, if you or your family members are experiencing chronic gastrointestinal distress, see a doctor.

If your well water has tested positive for microorganisms, you can treat it the water with shock chlorination, ultraviolet (UV) light, distillation, or ozonation to kill bacteria and other pathogens. 

If you’re interested in UV treatment or distillation, see our lists of the best UV purifiers and the best distillers to choose one you can rely on.

Remember, though, these are just temporary solutions. You must find out why your well is contaminated with bacteria and have it repaired or replaced.

Nitrate and nitrite

Nitrate and nitrite contamination in drinking water is another common concern among private well water owners. 

Unsupervised animal waste disposal, such as may happen near farming communities, exposes clean groundwater to nitrate and nitrite as the waste is broken through natural processes.

Agricultural fertilization also causes nitrate contamination in groundwater. Fertilizer can also cause problems in groundwater where it’s heavily applied to lawns.

Another situation to watch out for is a leaky septic system. If your septic system is leaking into your well, the water you pull from your well may be contaminated with nitrate and other impurities you don’t want to be drinking.

One health concern associated with this toxin is the deadly methemoglobinemia — a disorder that targets children, specifically bottle-fed babies.

Some studies even suggest that drinking water contaminated with nitrates can cause cancer.


The Environmental Protection Agency (EPA) suggests that the safe limits of nitrates and nitrites are 10 mg/L and 1 mg/L, respectively.

The most practical way to prevent nitrate contamination in drinking water is to install a reverse osmosis (RO) system, but ion exchange technology and distillation have also proven effective at removing these toxins.

For more about removing nitrates from your water effectively, read up on the best reverse osmosis systems for well water.


Arsenic occurs naturally as a mineral deposit in some regions, while in other locations it results from industrial practices, such as mining. For instance, groundwater in New Hampshire and Maine has high levels of arsenic in bedrock.

This toxin can stop production of red and white blood cells and damage blood vessels.

It is associated with heart disease, a “pinching” sensation in hands and feet, irritated respiratory system, and sore throat.

Research shows that prolonged ingestion of inorganic arsenic can lead to cancer in the liver and skin.


According to the EPA, if your drinking water has an arsenic quantity greater than 10 ppb, immediately stop consumption and shift to another drinking water source.

Arsenic is not absorbed in the body through the skin, so if you’re using well water contaminated with arsenic, you can safely use it for bathing and cleaning purposes.

However, I’d suggest you treat the water because you’re still at risk of inadvertently ingesting arsenic.

Better safe than sorry.

Arsenic can be a little tricky to remove because its filtration can be hindered by other elements, such as iron and manganese, present in the water.

It exists in two forms, “arsenic 3” and “arsenic 5.” Treatment involves converting arsenic 3 to arsenic 5 through air injection oxidation because it’s easier to filter out.

I advise you to ask your lab to test the concentrations of both types of arsenic so you can decide which water treatment process is best suited to your needs. 

The best arsenic removal methods include ion exchange, reverse osmosis, and activated alumina.

Check out our list of the best whole-house filtration systems for arsenic removal.

Other heavy metals

Other than arsenic, metals and metalloids, such as copper, lead, chromium, selenium, iron, manganese, and other contaminants are naturally present in trace amounts in the ground.

They’re also found naturally in food as essential nutrients humans need. However, in elevated concentrations, they cease to be beneficial and become problematic.

Increasing human activities, like mining, farming, and manufacturing, are constantly adding contaminants, including heavy metals, into groundwater sources.

However, the most common causes of metal contamination in well water are deteriorating plumbing pipes and rusted fittings inside the well. If your well is 15 years old or older, the pipes might need some repairing, or even replacing.

Concentration of any of these metals exceeding safe limits can cause health risks such as kidney, liver, and intestinal disorders.

  • Copper concentration exceeding 1.3 ppm (EPA limit) can cause vomiting, diarrhea, stomach illnesses, and cramping. If you identify bluish green stains on copper fixtures, that’s copper corroding away and entering your well water.

  • Lead is so harmful to the body that the EPA has set its safe limit to “zero.” It accumulates in the body over time and damages the central and peripheral nervous system — especially in children.

  • Iron greater than 0.3 g/L in well water may stain your fixtures, laundry, and dishes. High iron concentrations can damage the heart and liver and cause nausea and stomach pains.

  • Chromium exceeding 0.05 mg/L leads to skin rashes and disturbs the liver, stomach, and nervous system. If consumed for an extended period of time, it can even cause death.

  • Calcium and magnesium are responsible for hard water and are treated using an ion exchange water softener. While not of particular concern to human health, hard water is tough on appliances, laundry, and skin and hair.


If your drinking water tests positive for metals and elements in quantities higher than the safe water benchmarks mentioned by USGS, the best solutions include replacing your well pipes and fittings, flushing the pipes to remove sediment contamination, and installing private purification systems.


Radionuclides like uranium, radon, and radium occur naturally in bedrock.

However, they are also often introduced to the ground from unregulated coal, oil, and nuclear industry waste disposal.

Such contaminants can cause cancer in various organs.


The EPA suggests reverse osmosis and ion exchange as effective treatment for the removal of radionuclides.

However, radioactive material will collect on the RO membrane or ion exchange resin, and it needs to be disposed of carefully. See this page from the EPA for more info.

Organic chemicals

Volatile organic compounds (VOCs), synthetic organic chemicals (SOCs), and “forever chemicals” (PFAS, PFOS, PFOA) can seep into the groundwater due to unmindful disposal of gasoline, pesticides, degreasing agents, dyes, paints, and pharmaceuticals.

Long-term exposure to these pollutants damages kidneys, respiratory organs, cardiovascular and reproductive systems, and immune systems, as well as being linked to cancer.


Carbon filters, aeration, and reverse osmosis systems can help get rid of organic contaminants in well water.

Causes of Well Water Contamination

You might remember from science class that water is an excellent solvent because it can dissolve many salts and chemicals. This is the reason your groundwater is susceptible to contamination.

Let’s discuss some of the major causes of well water contamination and how you can avoid them. 


The most common cause of well water contamination is nearby surface runoff contaminating groundwater before it makes its way to your well.

During heavy rainfall or snow, contaminated water can seep through the surface and sneak into your well water source.

The dirty surface water runoff brings with it harmful bacteria, viruses, parasites, organic chemicals, heavy metals — all sorts of toxicity present on the surface of the earth.

Yes, I’m talking about human sewage, chemical fertilizers, animal waste, oil spillage, and other industrial pollution!

Although there’s nothing much you can do about preventing the dirty water from absorbing into the ground and entering your water source, you can treat the well water itself, seal the well head, and make it watertight.

Location of the well

Another essential factor is the region where you’re located. Groundwater quality varies from place to place. Some locations offer squeaky-clean water, while other sites have a lot of mineral content in the ground, contaminating the groundwater with excessive salts.

For instance, groundwater in the northern US is quite saline because salt is regularly spread on roads to melt ice, which then absorbs into the aquifers.

If your well is situated near a farm where fertilizers and pesticides are used in abundance, it will catch some of those chemicals.

Additionally, a well located near a gas station, defective septic tanks, leaking underground storage tanks, or landfills may be the cause of unsafe drinking water.

Before buying a property that will use a private well, you’ll want to find out what kind of industry or other sites are in the community. It may help you decide what kind of filtration you should expect to need, or if you want to buy the property at all.

If you already have a property with a well, again, you should test it annually, especially if it meets any of the above conditions.

Condition of the well

Lead pipes and old pumps can also be a source of water contamination. Sometimes, old brass fixtures and rusting iron can leach harmful toxins into the drinking water. Faulty structures, such as inadequate concrete casings and leaky covers, can allow dirt to enter private wells.

If your private well is old and rusty, immediately replace the old copper and brass fittings with new ones and investigate your well structure regularly.

Remember, the average lifespan of a well is 30 to 50 years, so if yours is older than that, it may be time for a new one.

Final Thoughts

Well water is safe to drink, but you shouldn’t take it for granted.

Just because your well water looks sparkly clean and tastes nice doesn’t mean it’s free of harmful contaminants. You can only know what’s inside by testing your water in a laboratory. 

Thanks to human and industrial activities, groundwater and water quality are always susceptible to changes.

So, your take-home message is this: water from private wells is only safe to drink with frequent water testing and proper water treatment systems in place.

For more information about water treatment and private wells in general, check out these helpful articles.

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