Installing the AquaTru Under Sink RO System
One of the most important — and often overlooked — components of a healthy home is having a high-quality water filtration system. Clean, filtered drinking water impacts everything from hydration and cooking to long-term health. In this project, we’re taking a closer look at the AquaTru Under Sink reverse osmosis system, specifically at how we installed it to save valuable kitchen space.
We’ll also show how we routed filtered water not only to the kitchen sink but also to the refrigerator — something that’s often overlooked in many homes.
Why We Chose the AquaTru Reverse Osmosis System
What immediately stood out about the AquaTru Under Sink reverse osmosis (RO) system was how simple and user-friendly the filter changes are.
Tested & Proven Purity
AquaTru products have been tested to rigorous standards by IAPMO to NSF / ANSI tested by a third party and proven to reduce contaminants for their full filter lives, which range from 300 to 1200 gallons.
They believe in transparency and offer their purifier performance data sheets that outline the contaminants and removal rates of harmful toxins!
Many RO systems on the market are incredibly complicated. The filters can look like something out of space, and the process is so confusing that homeowners end up not changing them at all. In fact, I have another RO system in a different house that’s so difficult to maintain, it rarely gets serviced the way it should.
The AquaTru system solves that problem with color-coded, easy-to-swap filters:
- Pre-carbon filter (yellow) – easily pops in and out
- RO membrane filter (blue) – the core reverse osmosis membrane
- VOC carbon filter with pH mineral boost(green) – included in the alkaline version of the under-counter model
This is a four-stage reverse osmosis system, clearly laid out as:
- Stage 1 & 2
- Stage 3
- Stage 4
No tools, no complicated housings — just straightforward maintenance that actually encourages proper filter changes.
Understanding the RO Tank and Space Considerations
This AquaTru Under Sink system includes a 3-gallon RO tank designed to fit under a kitchen sink. While it can be installed there, it’s essential to understand how much space it consumes.
Once you factor in…
- The RO tank
- The mounted filtration unit
- Sink plumbing and drain lines
- Garbage disposal
You can easily lose half or more of your under-sink storage space. If you store cleaning supplies, trash bags, or anything else under your sink, this can become a genuine inconvenience.
Some RO systems even use larger tanks, which makes the space issue even more pronounced.
Why We Didn't Install AquaTru Under the Kitchen Sink
Instead of installing the AquaTru RO system under the sink, we chose to locate it in the home’s utility closet.
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This home already has:
- A water softener system
- A tankless water heater
- Electrical components
- Low-voltage wiring
- Humidistats
- Radon system components
Keeping everything centralized in a single utility space makes long-term maintenance much easier.
Utility Closet Installation Details
- The RO filtration unit is mounted on the wall
- Backing was installed in the wall to allow flexibility in mounting height
- Filters are easily accessible — you can walk in and change them without crawling under a sink
- The three-gallon tank will either sit on the floor or on a small platform once final flooring is installed
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Plumbing the System: PEX-A and Legend PERT Pipe
The main water supply feeding this system also serves:
- The fire sprinkler system
- The water softener
- The water filtration system
- The reverse osmosis system
The plumbing setup includes:
- A ½-inch PEX-A line
- Legend PERT pipe with expansion fittings
This line feeds water from the RO system down to the kitchen. From there, we routed the line so it could serve both the kitchen sink and the refrigerator, ensuring all drinking water and ice are properly filtered.
Delivering RO Water to Both the Sink and Refrigerator
One common mistake with reverse osmosis installations is only running filtered water to a small faucet at the sink. At the same time, the refrigerator continues to use unfiltered water for ice and drinking water.
In this home…
- The RO supply line runs from the utility closet down to the kitchen.
- Under the crawl space, we installed a T-fitting.
- One branch feeds the kitchen RO faucet.
- The other branch feeds the refrigerator water supply.
- The refrigerator line is insulated, especially where it runs through exterior walls.
This ensures:
- Clean RO water at the sink
- Clean ice and drinking water from the refrigerator
Keeping the Space Under the Sink Open
Because the RO system lives in the utility closet:
- The cabinet under the kitchen sink remains fully usable
- No bulky tank or filtration unit is taking up storage space
- Maintenance is easier and more accessible
This approach works exceptionally well in:
- Custom homes
- ADUs
- High-performance or healthy home builds
- Homes with dedicated utility closets
Final Thoughts on the AquaTru Under Sink RO System
To recap, the AquaTru Under Sink reverse osmosis system works perfectly as an under-sink system. But if you want to maximize storage and improve accessibility, relocating it to a utility space is a smart option.
You’ll need:
- A ⅜-inch or ½-inch water line
- PEX, copper, or PERT pipe
- Proper routing to serve both the sink and refrigerator
The result is clean, high-quality water throughout your kitchen without sacrificing valuable cabinet space.
Need Help?
If you need help building a custom home, ADU, or whole-house remodeling, request a project consultation with us. We have offices in Ramona, California, serving the San Diego County area, and Middleton, Idaho, serving the Boise Metro area. You can also explore our comprehensive collection of similar videos on our YouTube channel, The Real Property Show.
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