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Undersink Water Filters

Kitchen Water Filter or Reverse Osmosis System

designed by ecologist James P McMahon

Which Do You Need?

Buy the kitchen water filter or reverse osmosis system that removes the contaminants in YOUR water

This page describes the Kitchen Defender™ water filter and Sweetwater's custom reverse osmosis system (below)

 KD kit 2020 web

Sweetwater's Kitchen Defender 4 stage kitchen water filter with installation kit


The Kitchen Defender™ sells for $386. plus shipping, typically $40

The Kitchen Defender™ water filter is the most comprehensive undersink water filter available. 

The Kitchen Defender removes:

  • fluoride* and arsenic
  • chlorine and chloramine,
  • chlorine byproducts known as the trihalomethanes and haloacetic acids. 
  • pesticieds. 

* fluoride may be removed or reduced depening on water chemistry. For complete removal see Sweetwater's Custom Reverse Osmosis (below)

 Kitchen Defender under sink filter


There are many undersink water filters. How do you tell them apart? And there are reverse osmosis systems, also known as water purifiers. Which do you need? How do we determine which undersink water filter is appropriate for you?


What you need depends on the contaminants in your water. Learn how we determine what you need:

First...I speak with every customer by phone and actually look at your water quality report, review the contaminants present, and provide the product that will remove those contaminants from your water. If you don't do that you can't possibly know whether you're buying the best product for your situation... won't find a shopping cart on this website. You call me to discuss your situation and we make absolutely sure you're getting the system that you need. You tell me your goals and I'll tell you whether a kitchen water filter or reverse osmosis system will meet those goals. I'll tell you what I would buy if I was drinking your water. The focus of my work is your health. Most of my competitors focus solely on the taste of the water or confusing you with exaggerated claims. Don't be fooled!  TheThe



The water tastes so much better than provided by my old filtration system.  After installation of the Kitchen Defender, my water is clear, smells fresh, is nicely aerated with tiny bubbles, and is quite good.  It's still not so "sweet" as the best mountain waters of my memories (Ah... the summit at Lassen State Park in No. California -- I hated to leave that spigot on the roadside!)

 Randy Krelle; San Francisco

 Kitchen Defender with owr

 Kitchen Defender with water revitalizer on the upper right and leak detector


Do you want the very best undersink water filter?

The answer is complicated. What you need depends on what contaminants are in your water to begin with. I refer you to my discussion on that topic here, but if your water supply is clean enough that a kitchen water filter can remove the contaminants then my Kitchen Defender is superior to others on the market. It uses four separate technologies in three stages to provide you the most complete protection available: removing chlorine, chloramine, all chlorine byproducts, reducing or removing fluoride and arsenic, and providing a 5 micron sediment barrier. Besides chlorine or chloramine there are other carcinogens in your water. Of particular concern in every public water supply are the disinfection byproducts. The Kitchen Defender water filter will remove these while also removing or reducing fluoride. 

"Chlorine in water destroys protective acidophilus, which nourishes and coöperates with the 3 to 3.5 pounds13 of immunity-strengthening “friendly” organisms lining the colon, where about 60 percent of our immune cells operate.14 And chlorine combines with organic impurities in the water to make trihalomethanes (THMs), or chloramines."

 quoted from:

The Negative Health Effects of Chlorine

Joseph G. Hattersley

Send me your Kitchen Defender Specifications and PricingFi 


 Third... whatever I sell you will remove the contaminants in YOUR water.

The 3 stage Kitchen Defender™ water filter is ideal for city water that comes from a protected water source. One benefit of using Sweetwater's Kitchen Defender is knowing that you're using the best kitchen water filter for the purpose of making your water healthy - by removing the harmful chemicals added by public water systems. However in most cases the water calls for different treatment such as reverse osmosis.

A Chinese study using a filter with similar components to the Kitchen Defender showed that drinking filtered water makes you and your children smarter. (seriously - knowing that how can you continue to drink tap water?)

Some contaminants cannot be removed even by a high quality carbon water filter and will require a reverse osmosis system, which provides more thorough purification.  Examples include nitrates, pharmaceuticals, radioactive metals, and high dissolved solids (tds over 250 ppm). Reverse osmosis systems combine membrane technology with the filter technology like that in a kitchen water filter like the Kitchen Defender.

The point is: we don't know until we look at your water report.  That's why we talk. It would be much easier for me to sell online but then I would have no way of knowing if you've ordered the right product for your situation. Talking to every potential customer is exhausting but effective.

Please watch this short video which clearly demonstrates that chlorine is absorbed by your body when you drink unfiltered tap water:


Fourth... one of the first things I look at when reviewing your water report is the source of your water. If your water comes from a river and there are cities upstream of where you live then I will suggest you use my custom reverse osmosis system - due to the presence of extremely dangerous unregulated contaminants. These will not be listed in your water report because EPA does not yet regulate them. Please feel free to read this news story by the Associated Press in which drugs from upstream cities are present in the water of 43 million Americans:

Drugs in Your Water


Sweetwater's Custom Reverse Osmosis System

If your goal is to provide healthy water for your family then we must remove what the city has added as well as any unregulated contaminants if they are present. Only reverse osmosis will remove these. A reverse osmosis system is a water purifier. That differs from a water filter. You may read more about that here. I also recommend my reverse osmosis system for water with high total dissolved solids, nitrates, sulfates, arsenic, radioactive metals, hexavalent chromium and unregulated contaminants such as pharmaceuticals.


Sweetwater's custom reverse osmosis system

Sweetwater's 6 stage custom reverse osmosis system

Click here to request my Reverse Osmosis System Specifications and pricing


My custom reverse osmosis system for city water sells for $675 plus shipping- all orders are by phone

Custom configurations are available. I customize my reverse osmosis system to ionize the water, create an anti-bacterial environment inside the system and a final stage to raise the pH making it slightly alkaline. Other options are also available including UV light, arsenic removal, and removal of high dissolved solids.

The six stages include: sediment filter, KDF/catalytic carbon filter, carbon block filter, the RO membrane, the a carbon filter after the storage tank, and a calcite filter to raise pH.


Urban Defender and Sweetwater's RO

 This photo shows my RO with an oversized storage tank and pump mounted in the basement to serve multiple faucets in the kitchen above.


So....if you work with me we will transform your water and make it a vibrant source of hydration for your healthy lifestyle.

There are numerous online stores where you can buy the wrong product. No one else takes the time to look at your water report and make a recommendation.  Using my Kitchen Defender or custom reverse osmosis system guarantees healthy water for your family.

Finally, people often hear the rumor that reverse osmosis wastes water. I disagree. The process of reverse osmosis uses water to provide you with a high purity drinking water. An environmental life cycle assessment showed that using a reverse osmosis system at home was between 8 and 19 times more environmentally friendly than drinking bottled water.

 Sweetwater's custom reverse osmosis system

Sweetwater's custom reverse osmosis system - typical undersink mount


Product reviews:


"I want to say thank you for the best tasting water I've ever drank in my life"  - Johan Lorenzo, Loxahatchee, FL


"I can’t believe the difference in the water since I installed your Kitchen Defender, it actually tastes good, I have never noticed that kind of difference in any other filters I had over the years. Thank you."

Robin Antar, Brooklyn, NY

"Can I tell you how much I love your water. When we travel we bring it with us. And when we eat at friend's homes we bring it and they drink it too!"

 Heidi Marohn, Takoma Park, MD

For undersink filters that treat raw stream and rainwater see my rainwater page



"Wow! This water is really great.  It's like water I remember from when I was a child. Really delicious and boy does it make one great cup of coffee.  Thanks for your great product and excellent service."

 Terese Audino; Park Ridge, IL



"Jim, I was about to email you earlier but guests came by.  David finished the installation in about 10 minutes.  I flushed it out as you instructed.  And man, does that water taste good.  It tastes like WATER, not Clorox! Thank you again for all your help and for helping provide healthy water for my husband and me. 

Joyce Goza; Raeford, NC


Learn more about my Under Sink Water Filters

including pricing and custom options by calling me now:


Monday - Friday
9 AM til 5 PM
Mountain time



living water, water revitalizer

For 'living' water ask about
the Water Revitalizer!



“Dear Jim, you make me realize in a special way how our happiness depends on direct human relationships, with nothing standing in the way between full and honest communication of what knowledge each of us has.  Bless your enterprise.”

Russell DuPree, Freeport, Maine


I help people achieve healthy water in their homes

To read more about this topic see this Wikipedia article

"What's in YOUR Water?"

James P McMahon, ecologist
James P McMahon



I don't take American Express