How To Filter Water from a Well (With Common Contaminants)

If you own a home or are thinking about purchasing a home with a well then you likely have some concerns about the water quality you can expect.

You can filter water from a well by using whole-home filtration systems, under-sink filtration systems, refrigerator filters, or even basic ‘plug-in’ filters for your sink tap. Before setting up a well water filtration system, be sure to get your well water tested so that you know which kind of filter you will need.

Read on to learn more about the most common well water contaminants and the basics of installing a filtration system.

Common well water contaminants that need to be filtered out

Groundwater is typically clean because soil acts as a natural filter. As surface water percolates through the different layers of the soil, bacteria, viruses, and chemicals are filtered out.

That said, there are lots of contaminants that make well water unsafe. For starters, the average household uses lots of synthetic substances that are known to pollute ground and surface water. That is why you must purify well water before drinking it or using it for food preparation.

The most common well water contaminants that you are likely to find are:

  • Microorganisms
  • Heavy metals
  • Nitrites and nitrates
  • Organic chemicals
  • Radionuclides
  • Fluoride


Microorganisms include viruses, bacteria, and parasites that mostly come from human and animal waste although other sources are possible. If you have a septic system, you may want to do regular inspections to ensure it is not causing pollution to the groundwater.

Drinking water that is contaminated with microorganisms can result in all kinds of waterborne diseases (e.g., harmful algal blooms, hot tub rash, norovirus infection, swimmer’s ear, swimmer’s itch, dysentery, cholera, etc.).

Heavy metals

Heavy metals from industries, municipal waste disposals, natural minerals, and household plumbing can leak into the drinking water. Some of the heavy metals that are known to be found in drinking water include selenium, copper, lead, cadmium, antimony, chromium, and arsenic.

If you consume water that is contaminated with heavy metals, you might develop acute toxicity in your liver and kidneys or suffer from intestinal damage. Diseases like anemia and cancer have also been linked to heavy metals in drinking water.

Nitrites and nitrates

Most nitrogenous material in natural water typically converts to nitrate and so any source of combined nitrogen (mostly ammonia and organic nitrogen) should be thought of as a potential nitrate source.

The main source of organic nitrates is human waste and livestock manure. Ammonium nitrate and potassium nitrate from fertilizers are the primary inorganic nitrates that can contaminate your well. High levels of nitrites and nitrates in drinking water can cause methemoglobinemia or what is loosely referred to as “blue baby syndromeâ€

Organic chemicals

What do you do with your expired pharmaceuticals? Most people just flush them down the toilets, oblivious of the effects that can have on the environment.

If you have a septic tank, expired pharmaceuticals will not be broken down by the bacteria in the tank. This means they end up in the leach field and percolate into the groundwater. Other household organic chemicals that could pollute water include paints, dyes, pesticides, petroleum products, sealants, disinfectants, and any petroleum products. Consuming water that is contaminated with organic chemicals may result in damaged circulatory and nervous systems.

Other known effects include damage to the liver, kidney, and reproductive system.


Radionuclides are radioactive contaminants that can be found in water. They can appear naturally or as a result of human activity (e.g. mining of uranium, production of nuclear power, and coal mining).

Radionuclides can contaminate well water through wastewater seepage and clouding. As radionuclides break down (decay), they cause radiation, releasing dangerous toxins that can cause kidney failure and cancer.


Fluorides not only occur naturally, but it is also common practice for municipals to add them to water because fluoride plays an important role in strong teeth and bone formation. However, when in excessive amounts, fluoride can result in skeletal or dental fluorosis.

The CDC recommends a maximum fluoride count of 2 milligrams per liter.

How to filter well water

With so many possible contaminants of your well water, it is a good idea to use a water filter to ensure your water is safe for drinking and food preparation. Testing water is quite inexpensive as a DIY test kit goes for under $35 (here is a link to a good one on Amazon).

In fact, the EPA recommends that you test well water annually to ensure it is not contaminated. Most homeowners assume that their water is clean and safe for drinking because their water is clear. But most contaminants are usually dissolved in water and are therefore invisible to the natural eye.

There are many options for purifying well water but using under-sink reverse osmosis is the most efficient and cost-effective option. With an under-sink system, you won’t have to worry about any wastewater from the system, and the only maintenance is the annual replacement of the filter or as recommended by the manufacturer.

A reverse osmosis system uses a semi-permeable membrane to filter out contaminants from the water.

The RO system effectively removes all heavy metals, radionuclides, organic compounds, and fluorides from well water. But it does more than just eliminate the contaminants, it also improves the flavor of your drinking water. That is because it filters out the impurities that typically interfere with water taste.

Installing an under-sink filtration system is pretty easy, and any DIY enthusiast can hack it. But if you don’t want to get messy, you can ask a contractor to help with the installation. It just connects to your faucet so you don’’’t have to worry about installing another faucet for the filtered water. Just install it under your kitchen sink, and you will soon have access to safe, filtered water.

Under the sink filtration systems go for less than $200, and replacing the filters annually will cost just a few bucks.

You can also use a countertop RO filtration system. As the name suggests, you must place it on your countertop and then run your tap water through it. Countertop filtration systems come with their faucet, which you will then use to fetch your drinking water.

The main advantage of the countertop filtration system is you don’t have to mess around with your plumbing, just fix it on your faucet, and you are good to go. Here is an amazon link to a good countertop RO system that goes for under $150.

Final thoughts

Wellwater is exposed to many contaminants from natural sources and human activity. Even if your water source is an aquifer, it is best not to take your family’s health for granted.

The rule of thumb in matters of health is, it is better to be safe than to be sorry. That is why it is a good idea to purify your well water with a reverse osmosis system. Not only will the filtration system make the water safer for your family, but it will also improve the taste of your water. Besides, RO systems don’t cost an arm and a leg.