Membrane Solutions100 GPD RO Membrane, Reverse Osmosis Membrane with Membrane Housing, Replacement for Under Sink Home Drinking RO Water Filter System, Wrench,1/4" Quick-Connect Fittings,Check Valve

I originally gave this "DIY" RO filter and pressure vessel kit a one star rating because 99% of the water went out the waste (brine) outlet and there were only drops coming from my RO faucet.Well I didn't have everything I needed to get a usable amount of RO filtered water which would be being able to fill an eight ounce glass of water in less than a minute (vs a frikin day). With this 400GPD RO kit I was expecting to fill that glass in maybe 15 - 30 seconds based on what I have seen with a few of the full RO systems costing around $300-$400 that some of my neighbors had.After dealing with the seller's representative I would also give the seller (and his rep) a five star rating.The end result is that I am now getting the output I expected. As was my original review this new updated one is a bit 'wordy' . . .The reason I didn't get the expected output was more because of my lack of knowledge of RO systems. First of all in my defense for the scathing review and one star rating I gave I must point out that this is being marketed as a DIY kit. In my opinion it is not a DIY system - at least not a complete DIY. However it is a very good deal for a 400GPD filter kit that a Do It Yourselfer would need and want to build a complete RO system.To me a DIY product (stating "Make your own reverse osmosis water filter right now!") implies all I need to do is add these components to an existing filtered water line and feed the permeate RO filtered output to a dedicated faucet on my sink. While I didn't expect this kit to come with a RO faucet and some of the other parts I would need; I did (and still do) think this DIY kit marketed as it is should come with everything needed to put water into the RO pressure vessel and get a usable amount of RO filtered permeate water.However you need one more very critical component to get a usable amount of RO filtered water. That component is a Flow Restrictor (FR). With the Flow Restrictor you will be lucky to get even drips of RO filtered water. Without the Flow Restrictor there will be no back pressure to force water through the internal RO membrane and most if not all of the water will take the path of least resistance (practically no resistance) and go out the waste (brine) outlet of the pressure vessel. Basically this is why the container where the RO filter is placed is called a "Pressure Vessel" in the first place.Flow Restrictors (FR) are rated in what amount of restriction they place on the flow. It's not a 'one size fits all' deal. You need different sized FRs for different sized RO filters (50GPD, 75GPD, 100GPD and 400GPD etc.). Simply stated the amount of restriction needed is based on what you are putting in and and what you can except as an output. So there is a ratio if input to output. There are many more variables and it is more complicated than that but this is what it all boils down to.For most RO systems for every 3-4 gallons or raw unfiltered water you put in you get 1 gallon of RO filtered water out the permeate output. The other 2-3 gallons goes out the brine (waste) output and 'down the drain' so to speak. In the US where water is cheap and plentiful in most places some people might use the waste water output for watering the lawn, garden or taking baths or whatever other purposes. It's usually not 'bad' water coming out the waste output as the term waste implies.Also, If you don't want to have to open and close the input water line every time every time you open the faucet get some RO filtered water another component you will want is an (optional) Automatic Shut Off Valve (ASOV of ASO). If you are feeding the water into a holding tank or reservoir of some sort you would need at the least a float valve so that once the tank is full the input to the to the RO filter shuts off. This would actually be another type of ASOV.I only want RO water to drink where from what I understand a lot of people use RO water for aquariums, making maple syrup, hydroponic gardening etc. and use a more manual based system and may not use an ASOV - but I think that nearly all RO systems do and should.I did a LOT of online research before I bought any of the components to build my RO system and nowhere that I look was it pointed out that the FR is a critical component nor was a FR even mentioned.I already had a somewhat sophisticated filtration array in addition to a basic water softener for my rust colored well water with a very high amount of Totally Dissolved Solids (TDS). Bare in mind that a water softener does not remove any TDS it only exchanges the dissolved calcium and magnesium etc. solids of with sodium based dissolved solids so you still end up with about the same amount of TDS at the output as you had at the input.For washing clothes and showering the sodium based TDS was not a major concern for me but I didn't want any TDS or other crap (almost literally) in my drinking water. I should add that you DO want some calcium, magnesium and other TDS in your drinking water because your body does need some minerals. Unfortunately RO filters or 'throws out the good with the bad'. They actually make another 'filter' that adds back 'good' minerals into the RO filtered water after the RO filter. However you don't want a lot of other TDS in drinking water and some are very bad for your health.At the time I bought this 400GPD kit it did not come with a Flow Restrictor and the seller did not even sell them . . . or mention that one would be needed. In my correspondences with the seller I pointed this out. The seller contacted me after reading my review to find out what the problem was and replaced the kit at no additional charge. I have left a lot of bad and good reviews for many of my Amazon purchases I was impressed that the seller did so being for me this is not a common practice. I would rate the seller with 5 stars also.

We have very hard well water here, and have to RO all of our drinking, cooking, and gardening water. I have owned two packaged systems and built 3 from scratch for myself, family, and neighbors, so I have a lil bit of experience on what works and what does not.I upgraded from 2x 150GPD rated membranes that had been in service for nearly 2 years to this membrane. Very good production in the first 3 days in service. No RO membrane I have ever tried produces 100% of its label value under home pressure and temperature conditions. If you're getting 50% of label you're doing great, 30% of label is pretty normal. I am guessing I am getting about 120GPD actual output from this membrane, which is like 30% of label, so I am pretty satisfied.Injection is 80 psi, ~15C temp, ~1200ppm 7.4pH well water, and I get about 30ppm finished water. So if you're wanting this for super polished water for aquariums, its probably not a good choice. But for home drinking and cooking and gardening water, it is a great choice. A few minerals left in it helps to keep the pH from crashing too low once the water gets a chance to interact with the CO2 from the air to make carbonic acid.Suggestion to Membrane Solutions: add the integrated check valve fitting instead of just a straight elbow!Wrap all the fittings in PTFE tape! I usually do 6 wraps of .35 thickness, but you probably want 10 wraps on these fittings as the threads have a lot of clearance with the housing.Overall, great value for money. Think I will be sticking with Membrane Solutions brand from here on out.

Great product

Check valve on RO Membrane failed after only 6 months resulting in no water flow from RO which had to be replaced.

I hooked this up to an existing 50gpd unit 5 stage and wanted a little boost. I replaced the existing RO membrane and housing with this one and I installed all new filters while I was at it. here are my results.My system in order of how the water flows through the system.1-micron sediment filter.5 micron carbon block.5 micron carbon blockRO membraneTwo 20 gallon RO well tanksCons.1. The fittings that come with this are useless and garbage, they leak even with a very generous amount of pipe tape. I think the threads are just to small and they felt very sloppy while threading them into the housing. Get new fittings, I used sharkbite fittings they fit nicely.2. it does not come with a check valve which on a normal RO membrane housing that includes fittings the check valve is on one of the fittings for the RO water outlet.3. At 90 PSI going in with (all pre-filters are 10in) 1-micron sediment, and two .5micron carbon blocks before the membrane I am producing 155 GPD so not quite as advertised. When I pushed it to 100 PSI I was getting 181GPD.4. They supply you with two 1/4in 90-degree push connects and one 3/8in straight push connect. I have 1/4in coming from my filters so I had to pick up a 3/8in to a 1/4in adapter to make it work.Pro.1. TDS meter hooked up. Inlet 190-198, outlet 8-12. So pretty happy about that.2. Housing seems to be good quality and feels robust.3. Once you install new fittings leaks are gone I used shark bite brand fittings, they never fail.Conclusion...I am using this for drinking water only and for that it's a great deal considering the price, but for my reef tank, I still use the Bestvalue RO 50GPD unit that produces a constant 0 TDS even after a few thousand gallons. I would not recommend this for reef tanks. For drinking water, freshwater fish tanks or just some fast cheap RO this is a great deal.

Works like they should

Works great

Good quality product. Packaged well, and prompt shipping.