Reverse Osmosis System for Well Water: More than Just a Water Filter

Reverse Osmosis Systems for Well Water: Homeowner's Guide

Are you concerned about the quality of your well water?

A reverse osmosis system is a great way to remove contaminants from your well water and improve its quality. But deciding which type of reverse osmosis filter is best for your needs can be difficult.

That’s why we’ve written this guide about using a reverse osmosis system for well water.

It covers common contaminants found in well water, provides testing recommendations, and lists many of the challenges associated with well water. Our guide also explains what reverse osmosis is, how it works, and which contaminants it can remove.

The information in this article can help you decide which type of reverse osmosis filter is best for your needs. Continue reading to learn more about reverse osmosis water treatment and well water.

Reverse Osmosis

reverse osmosis filter to remove TDS

Reverse osmosis, or RO, is a type of water filtration system that removes impurities from water by forcing it through a semi-permeable membrane.

RO systems are effective at removing a wide range of contaminants, including bacteria, viruses, protozoa, and sediment. They can also remove some chemical pollutants, such as lead and arsenic. These water systems are simple to use and easy to install.

How reverse osmosis works

Reverse osmosis works by using water pressure to force water through a semi-permeable membrane. The pores in the membrane are small enough to allow water molecules through, but they’re too small for most contaminants.

As the water is forced through the membrane, the contaminants are left behind. The clean water is then collected on the other side of the membrane. The concentrated wastewater is flushed down the drain.

Components of a reverse osmosis system

Typical reverse osmosis systems employ a multi-stage process to improve water quality and improve its flavor and smell. These systems include a particle filter to remove sediment, rust, and turbidity.

RO systems also have a carbon filter to remove chlorine that can damage the semi-permeable membrane. The membrane is the component that removes contaminants and impurities to very low levels.

If you have low water pressure (less than 45 psi), you may need a booster pump for the reverse osmosis membrane to function properly.

The treated water is stored in a small tank until it is dispensed from the tap. This provides enough water to quickly fill a glass for drinking or pot for cooking.

Which contaminants does reverse osmosis remove?

Reverse osmosis systems can remove a wide range of contaminants, including bacteria, viruses, protozoa, and sediment. They can also remove some chemical pollutants, such as lead and arsenic.

A reverse osmosis system water filter is able to remove the following contaminants and impurities.

ContaminantRemoval Efficiency
Arsenic + 370-80%
Arsenic + 594-99%
Total Dissolved Solids95-99%
Bacteria> 99%
Protozoa> 99%
Ameobic-cysts> 99%
Giardia> 99%
Asbestos> 99%
Sediment/ Turbidity> 99%

Although RO membranes are great at removing iron and manganese, they can also be easily fouled by deposits from these substances, even if the concentrations are low. To avoid fouling problems, iron and manganese should be removed prior to reverse osmosis treatment using another treatment method.

System performance

Similarly, RO systems also have difficulty with certain dissolved minerals, especially calcium and magnesium (hardness). These minerals can actually build up on the RO membrane, reducing its efficiency over time.

If you have hard water, you may need to install a water softener before or after the RO system to prevent mineral buildup on the membrane. Adding a storage tank can help with peak demand flow such as when you need to quickly fill a pot of water.

Well Water

Water quality is an important concern for many homeowners with private wells. While public water supplies are regulated by the Environmental Protection Agency (EPA), private wells are not. This means that it’s up to the homeowner to ensure that their well water is safe to drink.

Common contaminants

Well water can be contaminated with a variety of substances, including bacteria, viruses, chemicals, and metals.

Some of the most common contaminants found in well water include:

  • nitrates and nitrites – from sewage, fertilizers, and animal waste
  • microorganisms – bacteria, viruses, and parasites from human sewage and animal waste
  • organic compounds – house-hold products such as paints, fuels, pesticides, pharmaceuticals, VOCs, and solvents
  • heavy metals – lead from old pipes, heavy metals from industrial and agricultural activities
  • radionuclides – natural sources of radium, uranium, and radon are present in many rocks and soils

Bacteria and viruses are the most common type of contaminants in well water. These can cause serious illnesses if they’re not removed before drinking. Consider adding a UV disinfection system upstream of your osmosis unit.

Chemicals can also be present in well water, either from naturally occurring sources or from runoff from agricultural or industrial sites.

Challenges with water filters and well water

In addition to the contaminants listed above, well water often contains benign compounds that create a host of problems. These non-toxic substances include dissolved solids and gases, biological materials, organic matter from plants, and suspended particles. If your water has some (or all) of these compounds, you may need additional filters and treatment equipment to prevent fouling or degradation of your reverse osmosis system.

One common issue with well water is hardness. Hard water contains high levels of the minerals calcium and magnesium that can foul pipes and cause scale buildup on appliances. Although reverse osmosis can remove hardness, the membrane can become fouled quickly, so it’s often necessary to install a water softener before the RO system.

Testing your well water

One way to ensure that your well water is safe to drink is to have it tested regularly. Your local health department or a certified water testing laboratory can perform tests for bacteria, viruses, and chemicals. These tests will give you an idea of what’s in your water and what needs to be removed.

Factors to Consider with Reverse Osmosis Systems and Well Water

Reverse osmosis filters are a great way to remove contaminants from your well water. However, there are a few things you need to consider before installing an RO system.


RO treatment systems water filters can be expensive, both to purchase and to maintain. The initial cost of an RO system can range from $200 to $1000, depending on the size and type of system you need. Additionally, you’ll need to replace the filters every few months, which can add up over time.


Reverse osmosis filtration systems require regular maintenance to function properly. This includes replacing the water filters, cleaning the system, and flushing the membrane. Depending on the size of your system and the quality of your water, you may need to do this every few months or once a year.

Filter replacement is an added cost of having an RO system. Depending on the type of filter you have, replacement filters can cost anywhere from $20 to $100 each.

Water waste

Reverse osmosis systems reject some of the water as part of the filtration process. This rejected water is discharge down the drain as waste.

Depending on the type of RO system you have, it can reject anywhere from 20% to 80% of the water that goes through it. This can be a significant amount of water, especially if you have a large system or use a lot of water.

Filter speed (flow rate) – low water pressure

The RO filtration process is slow. Water often comes out at a very low flow rate. Depending on the size of your system, it can take anywhere from a few minutes to an hour to filter a gallon of water. If the water filters are fouled, then flow can drop to a trickle.

This can be an issue if you have a large family or use a lot of water. You may need to store filtered water in a holding tank, so you have enough for your needs.


Well water often contains microorganisms, such as bacteria and viruses. These can cause serious illnesses if they’re not removed before drinking.

Reverse osmosis filters will remove most microorganisms from your water. However, it’s important to disinfect your water after it’s been filtered to ensure that any remaining microbes are killed. This can be done with chlorine or ultraviolet light.

As you can see, there are a few things to consider before installing an RO system for your well water. However, if you take the time to understand your needs and choose the right system, you can enjoy clean, safe water for years to come.

Reverse Osmosis System for Well Water

There are two main types of reverse osmosis systems: whole house RO systems and point-of-use RO systems.

Whole house RO water filter system

whole house reverse osmosis system

Whole house RO systems treat all the water coming into your home. This type of water filtration is typically installed at the point where water enters your home, such as the water meter or well. This type of system is also known as a point-of-entry (POE) system.

Whole house RO systems are a good choice if you want to treat all the water in your home. This can be helpful if you have hard water, since it will remove the minerals that can cause scale buildup and other problems in your plumbing system.

Check out my comprehensive review of whole house reverse osmosis filters.

Under-sink RO water filter

Under Sink RO system

Under-sink RO systems are designed to treat the water where it is used. They’re typically installed under the kitchen sink, and they provide filtered water at that one location. This type of system is also known as a point-of-use (POU) system.

Under-sink RO water filtration is a good choice if you want to treat the water at one specific location, such as the kitchen sink. This can be a good strategy because you only treat the water you drink and not the entire house.

You can also purchase a countertop RO filter system to purify your drinking water.

Read my complete guide to under-sink RO systems.


Are reverse osmosis water systems good for well water?

A reverse osmosis filter system can be a great way to treat well water. It will remove contaminants, such as arsenic, lead, and organic contaminants from your water.

Is reverse osmosis water treatment a good idea?

As a homeowner, you may have to decide between a whole house RO water filtration system and an under-sink filtration system. If you want to treat all the water in your home, a whole house RO system is a good choice. If you only want to treat the water at one specific location, such as the kitchen sink, an under-sink RO system is a good choice.

How can I naturally purify my well water?

If your well water is contaminated, you may be interested in using natural purification methods to treat your drinking water. Examples of these natural methods include charcoal filtration and sand filters to remove impurities.


If you are among the many homeowners who get their water from a private well, then you know the importance of keeping your water clean and safe. A reverse-osmosis water filter system can be an excellent way to do just that, but it’s important to choose the right system for your needs.

We hope this guide has helped you better understand reverse osmosis systems for well water and given you some factors to consider when making your clean water system purchase decision.

Boch Richard

Richard Boch is a chemical engineer responsible for designing water filtration systems for industrial and residential customers. He has more than 20 years of experience with ion exchange, activated carbon, and reverse osmosis. Richard's expertise has made him a go-to source for municipalities and businesses looking to improve their water quality. When he's not working, Richard enjoys spending time with his wife and two young children.

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