GREATWELL ROG400 Tankless Reverse Osmosis Water Filtration System with 400 GPD RO Filter 1.5:1 Pure to Drain Ratio and Drinking Water Faucet
$598.99
About this item
- ROG400 is a tankless reverse osmosis system. The vertical filter placement design saves more than 30% of space under the sink compares to a horizontal design. A leak-free integrated water route and filter change indicator.
- The PAC filter is a combination of two sediment filters and a carbon filter that removes sand, rust, chlorine, odor, and smell. The RO membrane removes up to 99% of over 1,000 contaminants, including PFAS, lead, fluoride, arsenic, asbestos, and more for up to 3 years. The AC or the active carbon filter made from coconut shell further polishes water removing odor and bad taste.
- With a built-in water pump and GE reverse osmosis membrane rated at 400 GPD, the water flow rate from ROG400 is at 0. 3-0. 4 gal./min., with a pure to wastewater ratio (up to 1.5 : 1).
- DIY installation and future filter replacement. The unit can be connected to the ice maker/refrigerator. It includes an artisan-style stainless steel drinking water faucet.
- At GreatWell, we only use quality components tested by an independent 3rd party against NSF/ANSI standards. Lifetime technical support provided by our dedicated support team based in Atlanta, GA.
Frequently Bought Together

GREATWELL Tankless Reverse Osmosis Water Filtration System with 400 GPD RO Filter 1.5:1 Pure to Drain Ratio and Drinking Water Faucet
$598.99
- Availability: In Stock
- Model: ROG400
- Manufacturer: iSpring
Write Review
techteachok | 
2019-09-01
Bought this to replace 15 year old "tank" based RO water filter. My tank died (bladder went) and without a tank to buffer and deliver a few gallons quickly - my old 25 gal per day rating on the RO was delivering its little heart out at its rated output of a little over a gallon an hour. Basically, put a gallon container under it, turn on, and come back in an hour. I wanted to get a better faster fill and not have a 5 gallon tank under the sink.
After install it took 2.5 min to fill a gallon container - much better than the "mathematical" calculation from 400 gal/day (3.6 minutes per gallon). Lastly, I like the ability to change the filters in the front of the unit, the wheels for easy movement under the sink, and how easy it was to install as a replacement.
Completely understood to get the performance of over 400 gal/day with a tankless system, the old style tank was replaced by a pump built into the water filter - BUT, didn't expect the pump to be as noisy as it is. Enough to stop conversation in the kitchen around the sink with folks saying what the heck is that noise. It would have been nicer to have a more silent running pump, which is my only real complaint. Took off 1 star for noisy pump.
Edit 5/1/2021: Read all the complaints about no filters available - I see they are available on Amazon, and I purchased a set from my local Home Depot, so, I don't understand the comments about no filters available unless you are in the middle of a desert.

2019-09-01
Bought this to replace 15 year old "tank" based RO water filter. My tank died (bladder went) and without a tank to buffer and deliver a few gallons quickly - my old 25 gal per day rating on the RO was delivering its little heart out at its rated output of a little over a gallon an hour. Basically, put a gallon container under it, turn on, and come back in an hour. I wanted to get a better faster fill and not have a 5 gallon tank under the sink.
After install it took 2.5 min to fill a gallon container - much better than the "mathematical" calculation from 400 gal/day (3.6 minutes per gallon). Lastly, I like the ability to change the filters in the front of the unit, the wheels for easy movement under the sink, and how easy it was to install as a replacement.
Completely understood to get the performance of over 400 gal/day with a tankless system, the old style tank was replaced by a pump built into the water filter - BUT, didn't expect the pump to be as noisy as it is. Enough to stop conversation in the kitchen around the sink with folks saying what the heck is that noise. It would have been nicer to have a more silent running pump, which is my only real complaint. Took off 1 star for noisy pump.
Edit 5/1/2021: Read all the complaints about no filters available - I see they are available on Amazon, and I purchased a set from my local Home Depot, so, I don't understand the comments about no filters available unless you are in the middle of a desert.
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ROG400 Manual