The internet is awash with information on well water filters, as well as advice on buying the best well filtration system.

But many people are skeptical of investing serious money in a filter that they may not need. Everybody wants clean drinking water, but nobody wants to overspend on an expensive system.

So, how do you know if you need a well water filter—and if you do, which type should you buy? Let’s look into it.

Scroll to:

• How do I know if I need a well water filter? (Water testing)
• Do I need a carbon well water filter?
• Do I need a sediment well water filter?
• Do I need a well water filter for bacteria and viruses?
• Do I need a well water filter and a well water softener?
• Do I need a whole-house water filter for well water, or is an under-sink filter ok?

The quality of groundwater is changeable and difficult to judge. Because of this, it’s hard to know how contaminated your water may be without testing it, using a home kit or professional service.

That said, there are a few things you can do to work out the chances of your well harboring unwanted chemicals and microorganisms:

Ask around

Talk to the previous owner

If you’re buying a property on a private well, make sure to have a conversation with the previous owner about water quality, pressure, and maintenance. You should be supplied with the results of the most recent well water test.

Visit your neighbors

Wells located in close together can vary significantly in terms of depth, pressure, and contamination. Despite this, it’s worth finding out if your neighbors experience any common issues with their water supplies. Visiting multiple neighbors will help you to build a picture of of local groundwater.

Survey your local environment

Weather patterns and flooding

Frequent heavy rain causes runoff, which can carry pollution into shallow wells and the surrounding soil. When an area floods, wells may need restorative treatment to remove microorganism contamination.

Well depth and location

Generally speaking, shallower wells are more susceptible to contamination from the surface, as well as those located nearer waste disposal units or the use of chemicals. An orange scum on the surface of water indicates an overload of iron.

Farming, factories, and fracking

The most common visible sources of groundwater contamination are large-scale industrial activities such as non-organic farming, manufacturing, and fossil fuel extraction. If you live in an area with lots of commercial or industrial activity, you must test your well.

The only way to know what kind of filtering you need for sure is to test your well water

Don’t commission water filter brands or salesmen to test your water.

They won’t give you false results, but they do have an incentive to sell you a filter! An impartial provider like The Home Depot is a better option.

Instead, you can test your well water yourself, using a home test kit.

Home testing kits are less detailed than professional services, but they should give you a reliable indication of any major contaminants. Home kits are sold online and in hardware stores.

Or, send a sample to an independent lab.

Local state-certified labs can also provide you with a detailed analysis of your water. By sending off a sample, you’ll receive a breakdown of exactly what’s contained within your supply, as well as an official certification for your well water.

For a full look at well water testing, here’s our guide on How to Test Well Water >

If the results of your test show that your water contains high amounts of volatile organic compounds (VOCs) such as benzene, chloroform, or trihalomethanes, then a carbon filter will help reduce these unwanted compounds.

Carbon filters are used to reduce levels of dissolved organic contaminants, which are a primary cause of bad tastes and smells in drinking water. These units use large blocks of finely ground, tightly packed carbon, which capture unwanted substances on their surface as the water passes through. 

If you add chlorine and other disinfectant chemicals to your well, carbon filters can also remove any remaining traces.

If your well water is cloudy or off-color, it may contain sediment. Sediment contamination is more likely to occur in wells dug into porous rock or connected to metal piping and may consist of silt, sand, stone, or rust.

Sediment filters are often the first element in a well water system, helping to filter out larger particles that may damage subsequent filters and the appliances in your home. These devices use replaceable or washable screens designed to capture all that dirt and muck.

(If you notice the amount of sediment in your well water has increased, it may be a sign of an issue with your well. This factsheet on sediment & well water from Water Systems Council can help you diagnose the problem.)

If the results of your well water test indicate the presence of harmful bacteria or viruses, then it’s absolutely essential that you treat or filter your water.

There are several accepted methods of reducing waterborne pathogens to safe levels. One is to disinfect a well using safe levels of chemicals such as chlorine.

Another is to use a reverse osmosis system that filters down to a fraction of a micron.

A third method is to employ a UV purifier, which disrupts the genetic makeup of microorganisms to render them safe to consume. Many well water systems include two or all three of these filtering stages.

Well water filter systems are often sold alongside water softeners and conditioners. This is for two main reasons.

The first is that groundwater is harder than surface water. Because it spends long periods under the earth, groundwater usually contains a higher amount of scale-causing minerals like calcium and magnesium than surface water sources like rivers and reservoirs.

The second reason is that well water filters are located at the point that water enters a home, which means that they service every outlet and faucet. During installation, many people also take the opportunity to also install a softener, providing pure, softer water to your shower, sink, and appliances.

Water filters and water softeners can be used independently and serve different purposes. Filter devices are designed to remove specific sets of contaminants while softeners and conditioners are made to deal with hard water minerals.

It’s also safe to drink hard water minerals. Water softeners are intended to increase the quality of water and reduce its impact on appliances and pipes, rather than affect water safety.

(Because reverse osmosis systems can filter down to molecular level, they do soften water. This means that you can use an osmosis system as both a filter and softener. However, very hard water will cause more wear and tear on an osmosis system than a designated softener.)

If your well water test comes showing safe levels of all potentially toxic contaminants, then you may not need a whole house water filter.

Instead, you may wish you filter your water at specific points in your home. An under-sink or countertop filter in your kitchen adds a barrier against potential contamination of your drinking water, in situations where filtering the water in your shower or laundry machine is unnecessary.

All well water should be tested on a regular basis to check for changes in its composition (many experts recommend annual testing. However, this is especially important if you choose not to protect your drinking supply with a filter system.