Contamination, slime, early membrane failure
I have been having serious issues with my reverse osmosis system. After diagnosing a prior issue involving a leak in the auto-shutoff valve and discovering slime in the system, and sanitizing the system (although maybe not well enough) and replacing the membrane, etc, I am now having the following issues:
1. My TDS is now over 175 coming straight out of the membrane housing (tested directly at the "good water" exit from the membrane housing). Taste has been pretty bad, too (not horrible, but not good), not sure if this is only because of the TDS or also the slime. The membrane is less than 2 years old (21ish months). The taste has been pretty bad for a while. My tap water reads about 600 on my TDS meter, for reference.
2. There was a pretty decent amount of dirtyish colored slime in the membrane housing (including a very small amount of red slime), and some in all of the other housings as well after and including the first carbon filter.
I am not sure if the two are related. Can bacteria eat through the membrane? I have tried to sanitize the system with bleach, but am about ready to give up on it. Am I going to need to toss it and get a new one?
I have been reading that flushing large amounts of hydrogen peroxide or bleach through the system can remove all the buildup, but I am unsure if this will actually dissolve the slime. I hesitate to do anything that involves washing parts in soap and water because I know there are many areas that I cannot reach, so if the sanitizing stuff will not do it on its own, I may as well not bother.
Is this a common issue with reverse osmosis systems? I cannot find much information on line about it. Is this from improperly sanitizing it or not being as careful as I should have during filter changes? Are the newer cartridge based systems (watts model ro-4 ro-pure) less susceptible to this type of problem since you throw out the entire housing? And, on that note, it seems they might be harder to sanitize since you could not add bleach to a sump housing to run through the entire unit?
This is a standard Watts Premiere system that I have installed. I believe the model number is 5SV, it is their standard "old-school" sump housing non-manifold model, "5 stage" including the final postfilter. It has a steel tank.
Last edited by holo; 02-20-2011 at 05:18 AM.
As great as RO technology is, it is not a cure-all and many factors can make it less than desirable. You didn't mention too much about the source water except TDS. What are other water conditions (hardness, well vs city, iron, etc.) are you dealing with? Red slime? Do you have any iron stains in the house?
Yes, bacteria can eat through membranes and that is why ROs are rarely awarded a biopure certification--although there are some that are. Once organic growth has penetrated the membrane and infiltrated the housings, lines, connectors, etc., a complete sanitiation process is recommended, or often a replacement may be better.
The pore size of membranes is far smaller than any bacteria (or virus) so they cannot penetrate the membranes. However, studies have shown under ideal conditions, they somehow are able a migrate across it but this is not something that usually happens in a short period of time with fresh membranes. Other means of transporting may be involved. This is not to say that these organics are dangerous or pathogenic but still not ideal. Handling membranes with unclean hands, for example.
I don't think soap will be of much benefit and that is why H202 or some other sanitiation solution is used. I prefer ROs with integrated cartridges. Owners with sump-style filter cartridges often do not take the time to sanitize them, check o-rings and other basic maintenance procedures.
Are you noticing the slime in the final filter? Do you have a steel or plastic storage tank? What type of drain do you have? Air-gap style? where does it drain into?
The source water is municipal water, in Phoenix, AZ. We are supposed to have pretty hard water, but I do not know the specific hardness or anything else about it really. I do not believe we have any iron in the water and have never seen any iron stains.
There are no iron stains in the house. There was only a very small amount of a dark red slime. This was underneath the black "lip" that seals the membrane, or around it.
I'm sure I handled it with unclean hands. I had no idea you had to be so careful with everything. The instructions do not make that clear at all.
As for the final filter, I can't see inside of it. It is of the type that has a connector on each side and just attaches to the lines. The tank is a steel tank and the drain is air gap in the faucet. It drains straight into a hole in the sink drain.
So, from your discussion of integrated cartridges I take it you like them much better? I take it they are much less susceptible to this type of problem? One of my concerns is that I would never notice it in the cartridge based system, where here I can take it all apart and see the slime.
To sanitize can I just dump a bottle of hydrogen peroxide in the first sump and run it through the system? Does it need to sit in contact for a period of time? Is standard 3% store bought H2O2 appropriate?
Last edited by holo; 02-20-2011 at 06:21 PM.
Do you have a softener or any other treatment on the system. The calcium in hard water will shorten the life of a membrane greatly. If you have a bio-film developed in the system it will be VERY hard to get rid of. Chlorine doesn't even always effectively resolve that situation if that's what's going on. Are there any reputable service companies in your area that could take a look? Maybe a lab you could take a sample of the red slime to?
I do not have a softener on the system. I understand that hard water will shorten the life of a membrane, but the last time I thought the membrane failed after a couple of years, Watts thought this was a very short amount of time to be outputting almost 1/3rd of the TDS of the feed water. Watts is a local company here, too, so they probably know the expected life here (our water is hard, but I do not think THAT hard, or at least they don't think so). Also, the problem last time ended up being a hole in my auto shutoff valve, which caused feed water to leak across to the filtered side. This is not the problem this time (and I had replaced the membrane thinking that was the issue last time, about 20-21 months ago).
Originally Posted by pawaterguy
There are service companies, but I do not know which are reputable and I hesitate to call any to clear out the system if it will just come back. As for the red slime, I wiped it off, so I could not get it tested. I hope it was not a dangerous microbe, but there was a very very small amount (maybe at MOST pea sized amount or less if you balled it up). It was separate and distinct from the regular slime and was underneath the black flap that is around the membrane about 1/3rd of the way down (it went all the war around the membrane, attached to that flap or under it, not sure). I would not have even noticed it had I not wiped off the membrane with a paper towel after removing it.
The dirtyish colored slime really just coated everything with a thin layer. The water left in the membrane sump housing was dirty looking too, I assume because removing the membrane detached a lot of the slime and stirred it all up.
Do you think this could be something dangerous? I would probably rather just go buy a new unit rather than call a service company, especially if that is what it will come down to anyways. I just really want to make sure that this is not just going to happen again if I put in a new unit (and replace all the lines etc). I have NOT been careful with everything and have certainly not sanitized my hands when touching everything (I had no idea it was that big of a deal).
Watts also did not seem surprised last time that there was some slime in my unit (or even seem to think it was a big deal). This is why I just did a small sanitation and put it all back together (some bleach in the unit, ran it through, don't really remember how much I used or anything). I assumed this was very common in RO units and that the annual sanitation just kept it down but did not eliminate it entirely and that it was inevitable and harmless.
Is it normal to get a thin biofilm slime type coating on the rubber seals of the prefilters and in the membrane housing? I have read a sparse amount of info online that talks about it occurring, but nothing really says whether it is normal or not. There is not much information. Thanks for the help guys.
Last edited by holo; 02-20-2011 at 09:10 PM.
the pinkish one is what interests me. that's generally an airborne bacteria that people see in toilets and whatnot...if they ever see it. here is a link to an article on it:
If it is indeed a biofilm then it will be much harder to get rid of. Here is some info on that:
Thanks... The red stuff wasn't really pink - more of a dark red. Regardless, I just went and bought a new Watts Premier Ro-Pure and am currently in the process of installing it. I cleaned out everything under my sink which was reawlly dirty and am currently disinfecting everything with bleach. Hopefully I have better luck with this system.
Originally Posted by pawaterguy
The biofilm link you sent, though seems directed more at municipal water supplies where there is chlorine in the system. I am not having any issues with a biofilm before the chlorine is removed from the system, but only inside and after the first carbon filter. Given the disinfection recommendations by these manufacturers I am gathering this is a very very common problem but not really discussed? I am still really wondering how I can prevent this from happening in the future since it seems inevitable. I guess you just have to replace these units every couple of years after the bacteria builds up to a certain level?
I missed it if you mentioned it. are you:
A: changing filters once a year?
B: sanitizing the unit each time you change them?
there really should be no need to replace the unit so soon if you're performing the regular maintenance I described above. obviously, without seeing the unit I was taking my best educated guesses based on what I see as a water guy. hope that helps. Also, the biofilm happens after the point where chlorine is gone from the system. It's not related to the chlorine to the best of my knowledge other than it grows where chlorine isn't...and once it grows chlorine has a hard time getting to the "critter" itself as it covers itself in the film thus preventing the chlorine to get to the root of the problem...which makes removal problematic.
Last edited by pawaterguy; 02-21-2011 at 07:22 PM.
I had been changing the filters once a year but I had not been that careful when I changed them to be sanitary about the whole thing. The sanitization I had not performed until recently. The whole unit was several (4-5) years old -- it was only the membrane that I had replaced a couple of years ago.
Originally Posted by pawaterguy
Underneath my sink I determined was also damp and musty -- the cold water connection to the sink had been dripping. I assume bacteria got in there during a filter change. I take it that it is not really inevitable that this film grows in all systems?
Nonetheless I just replaced it with a watts premier ro-pure system and fixed all the leaks and bleached the whole area under my sink. Hopefully this cures the problem. I did not reuse any old parts except for the old valve connecting to the water supply (which I assume was fine since only chlorinated water traveled through this valve). Hopefully this solves my issues -- we'll see if it happens again. This model seems much easier to maintain, though, in that the cartridges are completely disposable so that there are no sumps to sanitize. There are connections between the filter cartridges that are part of the unit, but otherwise... Hopefully this does not happen to me again. I was more careful this time to be sanitary about everything when installing it.
Thanks for the help. Is this a common problem in units that you service?
not really. I've had buildup in units that were never serviced at all before my arrival...but never in one that belongs to someone who has us service their system once a year (or more). Also, be sure to sanitize it at each filter change even with the new filter type. A little chlorine down the center of each filter will do. We're talking drops now...not pouring it in. Your membrane will thank you.
Ambiesis contamination from RO?
I just found out that the RO system I've been drinking water from for 3 months has not had filters or membranes replaced for years! The system has been in this house for 6 years, it may be that long! The reason I was questioning my father about it is because I've had diarrhea for 3 months. The lab confirmed an Ambiesis (amoeba) infection and prescribed an antibiotic which did nothing.
I'm racking my brain to figure out some other cause. Prior to 3 months ago, I was drinking Brita Pitcher water at home. Does anyone see a connection here? I think the system should be purged but I don't know how to do it and my father is 90 years old and slowing down. He's been the one I expected to maintain it.
Thanks for your input.