ICS-STP PolyHalt® Water Softener with Taste/Sediment Filters

Cascadian Water  |  SKU: ICS-STP
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Routine Maintenance Kit

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ICS-STP Water Treatment System

The ICS-STP is a cartridge-filter based water treatment system engineered to produce high-quality water for every use in home or business. It is three salt free  high-performance treatments in one small wall-mounted system. The ICS-STP combines our ICS-SP and ICS-TP treatment systems and is one of our top sellers. It is an excellent choice for city or well water.

Contains Two Filters:

Filter One:

The first filter is a high capacity multimicron sediment filter. This filter removes particles down to 5 micron to clarify the water and protect downstream treatment and the plumbing, fixtures and appliances.

Filter Two:

The second filter is a top quality activated carbon filter combined with Cascadian PolyHalt®. It is specially designed to reduce the total number of filters required for maximum treatment without increasing the overall size of the treatment system.

Water is first treated by passing through the activated carbon component to reduce chlorine, improve taste and odor, and reduce volatile organic compounds (VOC's).

After carbon treatment the water passes through PolyHalt® media where it is further conditioned to treat silica and blue copper staining which extends the life of plumbing, fixtures, appliances, windows and glassware etc., by protecting them from damage caused by untreated water.

Be sure the ICS-STP treatment system is right for you - take the Filter Finder Quiz.

    See product specifications below for more details

    Details for Replacement Filter ICS-STPK 

      Other Specs

      Filter Size: 4.5" x 20"

      Connection: 1" FNPT

      Treatment Included: S, Sediment T, Taste & Odor P, PolyHalt

      • Eco Friendly

        No Water Waste

      • Legal Everywhere

        Our filters can be used where salt softeners are banned

      • Easy Maintenance

        Change filters once or more per year

      • 60 Day Guarantee

        Return it, no questions asked

      Frequently Asked Questions

      Where does the ICS system go in my home?

      Where it can fit, and where it can easily get access to your home's water source. This is typically a garage, crawlspace, or even a closet. If you have questions a plumber would be able to help you find the best spot. During maintenance you'll need to fit a bucket and have enough space to turn the sump wrench which comes with your system

      How often do I replace the filters?

      Most people replace their filters once per year, or sooner if they start seeing issues with their water again. Learn about water issues here

      What is the return policy?

      If you are unsatisfied within 60 days of purchase, return the housing and we'll refund your purchase no questions asked.

      How fast do you ship?

      We typically ship same business day if the order is placed before 2 pm PST using UPS ground.

      Rely on our expertise to deliver the simplest water treatment

      Customer Reviews

      Based on 44 reviews
      Edward Smith (Oregon, US)
      New and improved water

      We moved into our new custom built home in 2023 and now have a year of real life experience using our duel filter Cascadian whole house water filter. In our previous homes we had salt based softeners that required monthly additions of salt leaving the water with that softened taste and mouth feel. And depending how the softener was calibrated, the water could be over-softened leaving it slippery and made rinsing shampoos and soap in the shower difficult. The monthly purchase of salt and lugging it to the softener was a pain.

      Now that we have a full 13 months of experience, we have been totally satisfied with our Cascadian Filter. The water quality is enhanced. The taste of the water is much improved over untreated city water. Funky odors and fluoride smell is gone. We have eliminated the need to buy bottled waters and we use a CO2 bubbler to make our own fuzzy drinking water instead of buying canned LaCroix. Glass in the shower stays clean with virtually no hard water deposits. Even our outdoor spigots are on the filtered system, so we can use it on our plants and grass. Salt treated water of old softeners can be hard on plants, so this was a benefit we didn’t initially consider.

      When it came time to change the filters at 12 months, I was anxious to see the condition of the used filters. The cartridges were easy to remove, the enclosed directions accurately demonstrated the best way to remove, clean and reassemble. The **** that the filters removed from our water was impressive, and energized our belief in the decision we made to not go with a traditional salt based softener. With four people in our house, plus two dogs and two cats, we fully tested our Cascadian system and it exceeded our expectations.

      Edward, thank you for sharing your thorough and enthusiastic review of our Cascadian whole house water filter! We're thrilled to hear it's exceeding your expectations in your new custom home.

      It's wonderful that you're enjoying the improved taste and odor of your water, without the hassle and drawbacks of a salt-based softener. The fact that it's benefiting your whole household – even the pets and plants – is truly a testament to its effectiveness.

      We're particularly excited that you were able to witness firsthand the impressive amount of 'crap' the filters removed from your water. Your photos are a powerful visual for others considering our system! It's clear that our dual-filter design is living up to its promise of comprehensive water treatment.

      Your positive experience with the filter change process is also valuable feedback. We strive to make maintenance as easy and straightforward as possible, so we're glad to hear our instructions were helpful.

      Thank you again for choosing Cascadian Water. We appreciate your support and are committed to providing you with continued satisfaction and clean, delicious water for years to come!

      Carol (Bozeman, US)
      No replacement o-rings

      I was expecting replacement o-rings. There were none in this package, only the lubricant and the gaskets for filter #2.


      Thank you for your feedback. We apologize that the replacement o-rings were not included in your order. As we discussed via email, our ordering process requires customers to specify their filter housing type to ensure the correct o-rings are included. We appreciate your understanding and look forward to serving you again in the future.

      MartyD (Dallas, US)
      Water filter

      I have a plumber replace the filters once a year. I have one set I keep on hand for the replacement and purchase a new one to have on hand. I live in an area with hard water and this filter cleans the water before it flows throughout the house. The water tastes clean.

      MartyD, thank you for the fantastic review! We're delighted to hear the ICS-STPK keeps your home's water clean and tasting great throughout the year. Smart planning to keep a spare filter on hand - it ensures uninterrupted enjoyment of soft, clean water. Thanks for choosing Cascadian Water!