This is a great product and the water tastes so sweet and pure! I have been using it for about 2 months. However, I gave it 4 stars instead of 5 because the part that holds the water to be processed in the back is VERY DIFFICULT to pull off the unit to empty and re-fill. Every single time, it is a struggle to pull it off the unit and the waste water usually splashes out. I have already chipped it, trying to pull it off. It's like it is vacuumed on and it does not want to let go. When it finally "gives" you need to be careful you don't get popped in the face, or bump it into something else. It's a fairly minor annoyance and I am still happy I bought it.

My husband was skeptical about a countertop reverse osmosis water filter system; now, he thinks this is a good option to a whole house reverse osmosis system. I wanted to try this particular model because of the glass carafe with an option to insert a filter for making alkaline water. This is our review about the machine after using it for 10 days.Size: Compared to our Berkee gravity-fed filtered water tank, the machine is more compact. It sits on the countertop next to our sink, which is convenient.Ease of use: Out of the box, you need to follow basic instructions to fill the tank and flush the system. The flush function is easy to use, there is a button on the control panel. We flushed the system with 4 tanks of water (the tank lifts out of back). The tank is easy to lift out of the 2 hooks that hold it in place, dump out and fill, then replace with a fresh tank.Capacity: The glass carafe with filter option holds 40 ounces, which is small. The plus is that one tank of water allows for 2 complete fills of the carafe (the control panel tells you when to dump out the tank and refill it with fresh water). It takes about 2 minutes to fill the carafe with 40 ounces of filtered water. For two people, it works well to set up the coffee maker and tea kettle the night before for our coffee and tea, then make fresh water in the morning for our water bottles for the day.Noise: It makes some noise, but it is manageable. We have an open-concept home with a kitchen, breakfast, dining, and all open to the living room. We can watch television in the living area while the machine is working. I would put this machine in a prep kitchen near the sink if we had that layout.Taste: The taste of the water with the alkaline filter placed on the top of the glass carafe is better than bottled water. The taste is also better than our Berkee gravity-fed system. Coffee and tea tastes great made with this water.Filters: The machine has 3 filters under the hood: C, PPC, RO. There are indicators on the front when it is time to replace the filters. It also has the option to place minerals into your filtered water that makes the water alkaline with a filter in the top of the glass carafe. In total, you will need to purchase 4 different filters for the machine.Control panel: The control panel has indicators for total dissolved solids before and after the water moves through the membranes and filters. It gives you options for flushing the entire system, and filling the carafe 1/3, 2/3, or full. It has an indicator to tell you when you dump the tank in the back (which has an integrated section to put the expelled TDS). It also has indicators to let you know when to replace the filters.

The Stokk E1 Reverse Osmosis Water Filter is a highly effective and convenient solution for anyone looking to improve the quality of their drinking water. This compact countertop system is incredibly easy to set up—simply plug it in, fill the tank, and flush it once. The 5-stage filtration process significantly reduces harmful contaminants, improving both taste and purity. After using it for a few weeks, the difference in water quality is clear. No more chlorine or unpleasant flavors, just clean, refreshing water every time. The unit’s design is sleek and space-efficient, making it an excellent addition to any kitchen. It’s easy to operate, with a user-friendly digital display showing the total dissolved solids (TDS) of both the incoming and filtered water, providing a real-time gauge of water quality. The included glass pitcher is perfect for storing filtered water, and it’s much easier to use than bottled alternatives. The Stokk E1 is a fantastic choice for anyone looking to enjoy high-quality water without the hassle of bottled water or complicated installation. Highly recommended!

I have well water and very hard water. I have two whole house filters, one to catch sand and such and another that is a charcoal filter then through a rust reducer water softener. All together it has reduced the hard water to about half of what it had been down to around 250 hardness.This has a display that shows input and output total dissolved solids (water hardness) but does that display actually TDH? I decided to see if it does. One of the things that had me wondering was the output had always showed 25, never changed. Real or faked? The input does change but has always showed about 250 or higher and increases as it dispenses water.First how this water filter works. Basically a reverse osmosis filter is a filter that the pore size is the size of a water molecule... anything bigger will not pass through but anything the size of a water molecule or smaller will pass through the filter. Using high pressure the water is pumped through the filter forcing water molecules through the filter. Any water that hasn't gone through the filter to be dispensed is "waste" water. This water is pumped back into the tank and as "pure" water is removed the concentration of "bad" water in the tank increases. So yes the input side hardness number should increase. This "bad" water is pumped through the filter several times which does decrease the total amount of water that will be waste water. It also increases the total dissolved solids in the tank water which the input number shows as increasing. It's also why the tank needs to be dumped and filled instead of just adding water to it without removing the tank.But that output side hardness number always showing as 25 still had me wondering.I have a water distiller so decided to use distilled water to fill the tank instead of filtered tap water, after two or three tanks of using distilled water the output hardness number started going down and then stayed as 8. It would take more then using a single tank of distilled water to show a change since there is an internal tank that would need have the "old" water flushed out of it.Not having scientific instruments to actually test the water the best I can do is make some observations. Distilled water uses heat to create steam that is cooled back into liquid water, anything that evaporates at or below the temperature that water evaporates at would also be distilled. Alcohol for example. So depending on what was in the tap water distilled water may not be only H20.Stokk E1 also has more then just the reverse osmosis filter. First there is a PPC Filter that "Removes Odor, Reduces Chlorine, Reduces VOCs, Reduces Sediment", then the reverse osmosis filter followed by a C Filter... Post reverse osmosis filter coconut shell Carbon Filter. This carbon filter "Improves taste by adsorbing off-flavors and odors in the water". To me this indicates it's for absorbing anything same size or smaller then a water molecule. OK so the output water hardness will never be zero.Back to the question of does the display actually indicates input and output total dissolved solids. From what I have tried I would say it does.I don't know how accurate it is but I would say the output TDS has to be pretty darn close with all the filtering my tap water goes through and then distilled and then put through the reverse osmosis then through a final carbon filter. If it shows tap water that starts out as 250 TDS outputs as 25 TDS and the distilled water shows output as 8 TDS it is measuring TDS and not just showing a fake display. I don't expect the display to be lab quality accuracy but it does show that the machine is actually doing something.Personally I consider a reverse osmosis filter as the best water filter and have for a long time wanted one but always thought dumping as much or more water as waste water then it produced as very wasteful. It's why I went with a counter top water distiller. This reverse osmosis filter recycles the water several times reducing the amount of water lost as waste water.When compared to my counter top water distiller the distilled water may be better with lower TDS... maybe... but it takes about 6 hours to produce a single gallon of water. RO water is also a good quality water and is much quicker to make. Anything larger then a water molecule should be filtered out with RO so water hardness should be on par as with distilled water. I'll likely put my water distiller into retirement and even use the water from the RO for my coffee makers.I would buy this again.

Good but very slow