Should I Install a Water Filter Before or After the Softener?

Adding a Pre-Filter Protects and Improves the Effectiveness of your Water Softener

Plumbed water softener in basement.
Plumbed water softener in basement.
Okay, so you’ve decided to install a sediment filter with your water softener, but you’re wondering if you should install the sediment filter before or after your water softener. A sediment filter should always go before your water softener. A water softener is not made to remove contaminants, that’ what a sediment filter is made for. A sediment filter installed before the softener will protect and prolong the life of your water softener.

What’s in Your Water?

You’ve probably heard it before, but the best way to know what is in your water and how to deal with it, is to have your water tested.

This is the only way to know for sure, what’s in your water and how to treat it.

Most people are reluctant to test their water, because it costs money and takes effort to send it to a lab. I get it, I tend to be frugal this way.

One simple and free approach you can do is to fill up a large clean, white container from your cold water and see if you can notice any discoloration or particles in the water. A white 5-gallon pail is perfect for this home test, or even your bathtub.

A large body of water is easier to spot murkiness or discoloration in water. You’ll also want to look for any particulates floating, or settling to the bottom.

Install a Sediment Filter, Just in Case

Clogged sediment filter.
Clogged sediment filter.
At this point, maybe you just want to put in a filter, just in case sediment may be present. This is especially a concern for those of us on well water, or those with older plumbing.

A water supply from a municipal source is less likely to have sediment and particulates in it, but it’s still not uncommon.

Maybe you already know that you want to install a sediment filter, because you’ve seen particulates in your water. In that case, I would suggest installing a Point of Entry sediment filter before your supply water makes it to your water softener.

This will remove anything that might make your softener less effective, such as dirt, silt, sand, and other types of sediment.

If you can find one, I suggest installing a clear filter-housing, so that you can visibly see the condition of the filter without having to close the valves and remove the housing for inspection. With a glance, I can quickly see the condition of my filter to see if it needs changing.

A dirty filter will have a thick coat of medium-brown colored sediment. As the sediment on the filter grows thicker with use, water pressure in the house gradually drops and is very noticeable.

Varying Levels of Contamination

Dirty sediment water.
Dirty sediment water.
At certain times, my well water can run fairly clean, where I don’t have to change my sediment filter for weeks. Other times, during periods of prolonged rains, or during prolonged dry weather, my sediment filter seems to become clogged much more quickly and I have to change it out about once a week to restore our water pressure.

At my place, when I turn on a faucet and find it’s flowing slower than normal, or if the pressure drops a lot when more than one person is running water in different parts of the house, I also know it’s time to change out my sediment filter.

The Water Softener is Also a Filter

The water softener itself is a filter. A water softener is meant to filter out calcium and magnesium minerals, not particulates and dirt. If dirty water is allowed to flow into the water softener, dirt can collect on the rotating valves in the controller and become inoperable. This is another good reason to install a sediment filter before the softener.

Water softeners will remove small amounts of iron, but are not specifically designed to treat high concentrations. There are more effective ways to deal with high iron levels. We’ll discuss this in another post.

Post Softener Filtration

Adding a carbon filter, placed after the softener will remove any chemical contaminants that may be present in the water, such as chlorine, and agricultural pesticides and herbicides.


A pre-filter is not necessarily needed for all water softener installations, but if your water comes from your own private well, installing a sediment filter is usually a necessity.

A whole-house filter housing with sediment filter can be low cost. A good one can be as little as $60. Replacement filters are also reasonably priced. If you have only a few particulates in your supply water, then it could be many weeks before you need to change out your filter.

This will assure that you’re protecting, not only your water softener to keep it working its best, but also protect your other water-using appliances (dish washer, hot water heater, clothes washer, reverse osmosis drinking water filter, etc.

So, it boils down to how clean your incoming water is. I think having a pre-filter before your water softener is a smart idea. It’ll extend the time between softener regenerations and help to prolong the life of your softeners resin bed.

These Crystal Quest Water Softeners come with both a sediment pre-filter, which protects the water softener, and a carbon block post-filter to remove chemicals, tastes and odors that may be present, for a well-rounded water treatment system.