What does “Post-RO” mean?

Post-RO means the unit installs after your reverse osmosis system, between your RO tank and RO drinking faucet.

Does this unit filter water?

No. It is not a filter and does not remove contaminants. It is designed to be used after filtration to support a more structured, revitalized water experience.

Will it work with my RO system?

In most cases, yes. It is designed for standard under-sink RO setups that use ¼” tubing.

Can I use it with a refrigerator or icemaker?

Yes. It can work with many ¼” tubing applications, including refrigerator water lines and icemakers. Confirm your line size before ordering.

Does it need electricity, batteries, or filters?

No. It is a passive system with no electricity, batteries, moving parts, filters, or cartridges.

Will it reduce water pressure?

Most customers do not notice a significant change in flow. RO systems naturally have slower flow than standard faucets, and performance varies by system condition, tank pressure, and tubing layout.

It is ideal for RO users who want smoother, more enjoyable drinking water after filtration—without adding a complicated system.

Post-RO Structured Water System

Name: Post RO Structured Water System
Brand: Natural Action
SKU: HD-9-RO
Price: 599.0 USD
Availability: InStock

Promotional infographic for an under sink water filter system, showing illustrated components including an RO system, a passive system canister, and a quick-connect faucet setup with water flowing into a glass.

Instruction graphic titled 'How It Installs' showing two illustrated panels: one with a blue under-sink filter connected to plumbing beneath a sink, and one with a faucet, tubing, and a glass under running water. Text explains connecting below sink and quick-connect tubing.

$599.00

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Vortex-Flow Technology Designed for Reverse Osmosis Water

Filtered First. Revitalized Second.

You've already invested in reverse osmosis to improve the quality of your drinking water.

Now take the next step with the Natural Action Post-RO Structured Water System (HD-9-RO).

Designed specifically for compatible reverse osmosis systems, the HD-9-RO installs after your RO storage tank and before your drinking-water faucet.

As filtered water passes through the unit, Natural Action's engineered vortex-flow pathways guide it through a passive, spiral-inspired movement process.

No electricity. No chemicals added. No replacement structuring filters.

A Simple Finishing Step for Your RO Water.

Why Choose the HD-9-RO?

Designed Specifically for Reverse Osmosis — Adds a separate water-structuring stage after your existing RO filtration.
Vortex-Inspired Flow Technology — Guides water through engineered internal spiral-flow pathways.
A More Enjoyable Drinking-Water Routine — Designed for customers interested in the taste and mouthfeel of their RO drinking water.
Easy 1/4-Inch Quick-Connect Installation — Compatible with many standard under-sink RO tubing configurations.
Everyday Convenience — Water passes through the revitalizer automatically whenever you use the connected faucet.
No Electricity or Batteries — Operates passively using existing water flow.
No Replacement Structuring Cartridges — No recurring cartridge purchases for the revitalizer.
Made in the USA — Backed by a 10-Year Limited Warranty and 90-Day Satisfaction Guarantee for eligible purchases.

The Benefits of Structured Water After Reverse Osmosis

A Different Approach to Your Drinking-Water Experience.

Reverse osmosis is designed to reduce specified contaminants through a filtration membrane and associated treatment stages.

The Natural Action HD-9-RO serves a different purpose: introducing engineered vortex-inspired water movement after filtration.

A More Refined Drinking-Water Experience

Some customers describe reverse osmosis water as having a flat or neutral taste.

The HD-9-RO offers an additional flow-form stage for people interested in how their drinking water tastes and feels.

Taste and mouthfeel are subjective, and specific improvements are not guaranteed.

Support Your Daily Hydration Routine

Convenient access to drinking water can help make regular hydration part of your everyday routine.

With the HD-9-RO installed beneath your sink, filtered water passes through the revitalizer automatically before reaching the connected faucet.

No countertop device or additional pouring step is required.

Water for Coffee, Tea & Cooking

Your RO system supplies filtered water for everyday kitchen use.

The HD-9-RO adds passive vortex-flow technology to water used for drinking, coffee, tea, and food preparation.

It may also be suitable for compatible refrigerator or icemaker lines, depending on the plumbing configuration.

A Finishing Step After Filtration

Filter First. Structure Last.

The HD-9-RO works with your existing RO system rather than replacing it.

Your reverse osmosis equipment performs contaminant reduction. The Natural Action unit adds a separate, passive flow-form stage before water reaches the faucet.

Long-Term Convenience

Once installed, the HD-9-RO operates whenever water flows through it.

There are no batteries, electrical controls, or disposable structuring cartridges.

One Simple Upgrade. Every Glass of RO Water.

How the HD-9-RO Works

Flow, Not Force.

Natural Action's HD-9-RO uses engineered internal flow-form geometry to guide filtered water through vortex-inspired pathways.

The unit is installed downstream of your reverse osmosis treatment system.

How the Process Works

Your reverse osmosis system filters the incoming water.
Treated water is stored in the RO tank.
When you open the drinking-water faucet, water flows from the tank through the HD-9-RO.
Water passes through the engineered vortex-flow pathways before reaching your faucet.

No electricity. No chemicals. No replacement structuring filters.

Important: The HD-9-RO Is Not a Filter

The HD-9-RO does not remove chlorine, lead, PFAS, bacteria, or other contaminants.

It does not replace your RO membrane, sediment filters, carbon filters, or other required treatment stages.

Continue replacing and maintaining your RO filters according to the manufacturer's instructions.

LEARN THE DIFFERENCE BETWEEN STRUCTURED AND FILTERED WATER

Installation & Compatibility

Designed for Standard RO Tubing.

The HD-9-RO features 1/4-inch quick-connect ports and is designed for compatible under-sink reverse osmosis systems.

Recommended Installation

RO System → RO Storage Tank → HD-9-RO → Drinking-Water Faucet

Turn off the RO water supply and relieve pressure according to the RO manufacturer's instructions.
Identify the appropriate 1/4-inch tubing line between the RO tank and drinking-water faucet.
Install the HD-9-RO using the quick-connect fittings and supplied tubing as appropriate.
Secure the unit using the mounting bracket.
Restore water flow and inspect every connection carefully for leaks.

Important: Confirm the RO system's plumbing layout, tubing dimensions, flow direction, available space, and manufacturer requirements before installation.

Professional installation is recommended if you are unfamiliar with under-sink plumbing.

VIEW INSTALLATION INSTRUCTIONS

What's Included?

Natural Action HD-9-RO Structured Water Unit
1/4-inch quick-connect ports
Approximately 3 feet of 1/4-inch tubing
Mounting bracket

Product Specifications

Feature	Specifications
Product	Post-RO Structured Water System
Model / SKU	HD-9-RO
Technology	Passive vortex-inspired flow-form engineering
Primary Application	Reverse osmosis drinking-water systems
Installation	Inline beneath sink, downstream of RO storage tank
Connection Size	1/4-inch quick-connect
Compatible Tubing	Standard 1/4-inch RO tubing, subject to compatibility
Dimensions	Approximately 12" × 2.72"
Weight	Approximately 3 lb
Electricity	Not required
Replacement Structuring Filters	None
Chemicals Added	None
Contaminant Filtration	Not provided
Country of Manufacture	USA
Warranty	10-Year Limited

Care & Maintenance

The HD-9-RO does not require replacement structuring cartridges or electrical maintenance.

Inspect tubing connections periodically and check for leaks.

Continue normal RO system maintenance, including scheduled membrane and filter replacements.

Which Natural Action System Is Right for You?

The Right Solution for Your Water Setup.

Don't Have Reverse Osmosis?

Under Sink Structured Water System (HD-9-US)

The standard HD-9-US is designed for compatible kitchen cold-water plumbing and uses 1/2-inch NPT connections rather than 1/4-inch RO quick-connect fittings.

EXPLORE THE HD-9 UNDER SINK SYSTEM

Want Filtration and Structuring Together?

HD-9 + Multipure Aquaversa

For customers who want a complete under-sink drinking-water solution, Natural Action combines its HD-9 flow-form technology with Multipure Aquaversa carbon-block filtration.

EXPLORE UNDER-SINK FILTRATION + STRUCTURING

Want Structured Water Throughout Your Home?

Whole Home Structured Water System (HD-24)

Bring Natural Action's vortex-inspired technology to compatible household water outlets with a main-line installation.

EXPLORE WHOLE-HOME STRUCTURED WATER

Not Sure Which System Is Right for You?

Take the 60-Second Natural Action Water Assessment.

Answer a few questions about your water source, existing filtration, and goals to find a recommended starting point.

TAKE THE FREE WATER ASSESSMENT

Buy with Confidence

Made in the USA

10-Year Limited Warranty

90-Day Satisfaction Guarantee

Natural Action Technical Support

Warranty and satisfaction guarantee are subject to published terms.

Frequently Asked Questions

What does the Post-RO Structured Water System do?

The HD-9-RO guides filtered water through engineered vortex-inspired flow pathways after reverse osmosis treatment and before water reaches the connected drinking-water faucet.

What are the benefits of adding the HD-9-RO after reverse osmosis?

The HD-9-RO provides a passive vortex-flow stage after filtration. It requires no electricity, adds no chemicals, and has no replacement structuring cartridges. Individual experiences with water taste and mouthfeel may vary.

Does the HD-9-RO improve the taste of reverse osmosis water?

Some customers report a difference in taste or mouthfeel after using the unit. These experiences are subjective, and specific improvements are not guaranteed. The HD-9-RO does not remove taste- or odor-causing contaminants.

Does the HD-9-RO filter or purify water?

No. The HD-9-RO is not a water filter or purifier. Your existing reverse osmosis system remains responsible for contaminant reduction.

Where should the HD-9-RO be installed?

In a compatible standard RO configuration, it is installed downstream of the RO storage tank and before the drinking-water faucet. Confirm the installation location against your RO system's plumbing design.

Will it work with my existing reverse osmosis system?

The HD-9-RO is designed for many under-sink RO systems using 1/4-inch tubing. Compatibility depends on tubing dimensions, plumbing layout, and equipment requirements.

Can I use the HD-9-RO with a refrigerator or icemaker?

It may be suitable for compatible refrigerator and icemaker water lines using 1/4-inch tubing. Confirm flow requirements, line configuration, and equipment compatibility before installation.

Does the HD-9-RO require electricity or replacement filters?

No. It operates passively using water flow and requires no electricity, batteries, or replacement structuring cartridges. Your RO system's existing filters still require regular maintenance.

Will the HD-9-RO reduce my water pressure?

Any inline device can introduce some flow resistance. The actual effect depends on RO tank pressure, tubing layout, flow rate, and installation conditions. Confirm compatibility if your system has limited flow.

What is the difference between the HD-9-RO and HD-9-US?

The HD-9-RO uses 1/4-inch quick-connect fittings for compatible reverse osmosis tubing. The HD-9-US uses 1/2-inch NPT connections for compatible standard under-sink plumbing. Choose the model that matches your installation.

Filtered First. Revitalized Second.

Your RO System Has Already Done the Filtration. Now Add Natural Action.

Bring vortex-inspired flow technology into your everyday drinking-water routine with the Natural Action HD-9-RO.

Add to Cart. Complete Your RO Water Experience.

Natural Action — It's Water, The Way Nature Intended.

I love my sink revitalize for RO systems

I love my sink revitalize for RO systems. There’s nothing like having structured, living water coming right out of your home kitchen faucet. Thanks again for bringing this hydrating miracle to my family and household!

Great combo with other products! Pure and structured!

We are very happy with our structured water devices! These devices are easy to install and the service is friendly and efficient. I have just bought another single tap for my parents. Highly recommended!

This unit along with a Frizzlife Under Sink Water Filter not only made our water taste amazing, it shifted the PH of the water from acidic to alkaline.

We've owned a hand-held NAT structured water filter for years, and have experienced the results first-hand, as well as introducing their technology to friends and family. It was only a matter of time before we upgraded and installed this one under our sink, and it significantly reduces our structuring time while keeping the water smooth, energized and happy. (yes, water can be happy... Google the recent scientific breakthroughs showing that water has memory!) Not only are we thrilled with the structuring, but NAT was able to ensure we received the product as expected and we experienced immediate and above-and-beyond customer service. What a great company. Our only other concern before buying this was that is might have been a counterfeit seller because of such limited reviews, but in good news this is the legitimate company and the product is 100% authentic. Thanks NAT!

5 stars: 15 (100%)
4 stars: 0 (0%)
3 stars: 0 (0%)
2 stars: 0 (0%)
1 star: 0 (0%)

I love my sink revitalize for RO systems

Great combo with other products! Pure and structured!

This unit along with a Frizzlife Under Sink Water Filter not only made our water taste amazing, it shifted the PH of the water from acidic to alkaline.

Thank you for introducing me to the Vortex Structured Water products. I love the portable structuriser. I take it with me everywhere I go for myself, family and friends. I love how much easier it is to drink water and how much quicker it seems to be absorbed from my stomach. For example, I can easily drink 0.5 to 1 Litre of water and exercise within 15mins at a very high level aerobically without any stomach discomfort. If I drink water straight from the tap, it rumbles around in my stomach for a long time (maybe 30 – 60 mins) before I can exercise comfortably. The difference is amazing.

I am very pleased with the quality of softness this unit has added to my water. I feel better and enjoy the purity this unit creates. Thank you!

I have continued my own home experiments drinking structured water which has me in such a state of euphoria, I couldn't begin to explain it. My skin was extremely dry — so much so, that my knuckles were split open. They are healed and my skin is smooth as a babies bottom in just a few days. Tap water tastes like bottled water. I have more energy than I did as a teenager. I am even putting some on the wrinkles under my eyes which are fading away. I am adding a life coaching service to my website which will give me a great platform for promoting your devices. Have a great day!

After hooking up the under sink unit that I purchased from you, I am convinced that what you say is true. It has empowered me to be at my best 24/7. I run a small electronics company and most days are very challenging.
My wife of 34 years seem to have grown in different directions. I was pretty normal when we got married but she thinks I am crazy now. So I started drinking the water and she has also. WOW, now I stay full of love most of the time, and it appears to have assisted my wife also. At this point in time I would like to spread this around.
I think I may be addicted, I get out of the shower and have to go to the basement and get some structured water. I wake up at night thirsty, I drink structured water. I love the way I feel. Honestly the water has helped me become a beacon of light 24/7.
THANKS

I was not an insomniac person, but very often if I would be awakened by any noise or the urge for a little pee, it would practically ALWAYS take me a very, very long time (between, one to two hours) to fall asleep again. Well, after 4 days – yes! Only FOUR days! – I was falling asleep again within 3 to 10 minutes maximum! I was really very surprised to have this result in such a short time. And, do believe me, there was nothing to do with the placebo effect, because I never thought of a result linked with my sleep. In addition, I definitely felt more energetic even as I am still very energetic for my ‘passport age’! (74 and a 1/2), but I am more of a 54 and a 1/2!

I was skeptical but this is crazy. I had it installed so that my water first goes through a reverse osmosis system them through the structure unit last. This water is crazy. It seems alive. I’m telling you, it moves. Hold it to light and it sparkles like champagne. I watered my plants the first day, then left town. Upon my return... I walked into a jungle. All the plants had grown so much in just three days. I actually can not use this water every time on my plants because all 23 plants out grew their pots and I can’t keep repotting everything. I also had to fertilize because they grew so fast they ate everything from their soil. So then I installed the shower structure unit in my shower. The difference in my skin and hair are very noticeable. And the water tastes really good. My friends filled up glass jars as they are leaving. Best purchase ever but, I do recommend a water filter system also to remove the chemicals first.

It helped me enjoy drinking water again. Went from 2-4 cups a day max to 2-3 liters a day. My body absorbed the water using your unit rather than going to the gents 10 times a day when I attempted to drink 2 liters + per day in the past Massive change. It tastes better! Made me feel more relaxed and less jittery for some reason. I can’t explain this. It made me calmer somehow… in the same way that meditation calms my mind, this “calmed my body” somehow by drinking more vortexed structured water. I have attempted to drink 1-3 liters a day in the past but my body didn’t like it – the taste and bloated feeling. This is easy to drink, no bloating! Ate much less food as drinking more water and light dinners so I seem to save food and money! I am convinced 100%. Big change!