Our new home has a reverse osmosis system under the sink, we have not replaced any parts or anything on it and are unsure if it is even doing anything anymore. I am pretty sure it is not filtering the hard materials out of it because I use a tea kettle everyday that I fill from the filtered water faucet - and it is getting lime deposits on the bottom of it.
Should I just replace the whole system? Seems silly, but a call to Rainsoft today said it would be $170 for the filters… :eek:
We’ll see, not sure what I am going to do, but does anyone have any idea how long these systems last? I understand it was a pretty good system in it’s hayday, but I’m guessing it was not used for the 2 years it sat before we got the house.
I have an RO system that is at least 15 years old. I’ve replaced the Carbon filter and the pre-filter a few times. The RO membrane is original, and the unit still delivers the best-tasting water in town.
RO filters don’t filter out 100% of dissolved solids, so lime deposits are not a good indication of how well your unit is working. Does the water taste different (hopefully better) out of the RO, compared with the tap?
There are three components to a complete water purification system. The RO membrane is the final step; think of it as a very fine filter, capable of removing individual molecules of dissolved contaminants. Like a very fine filter, it has a very low capacity, and is easily choked by sediment and high concentrations of dissolved material. So you need a couple of steps before that. The first step should always be a filter or two; really dirty water will need a prefilter to remove coarse sediment, and a main filter to remove fine sediment. The second step will be an activated charcoal filter to remove chlorine and organic contaminants.
Now the RO membrane can do its thing, which is to remove…, well, everything else. It will be exhausted rapidly by hard water, and if you’re getting a high flow of hard water out of your system, it’s not just worn out – either it’s being bypassed (look for a valve) or it’s busted. One other possibility is that the system takes a cartridge-mounted membrane, and there’s no cartridge in there. It’s also possible (likely, really) that your system has all of these components in a single cartridge, which to my way of thinking is a waste. Every water stream is different, and a house with rusty pipes requires a different balance between the filter and the RO membrane than a house with clear hard water.
Reading beowulff’s post, I feel compelled to point out that I assumed that by “new house” you mean that you moved in a month or so ago. While it’s true that RO doesn’t remove 100% of dissolved solids, it should be damn close, and lime deposits should not be visible in that time frame.
I should also point out that I’ve done a lot of simplification in my post; the industrial and laboratory grade water systems I’m familiar with are more complex than what I’ve described, and there’s a lot I don’t know about home systems.
If I remember right the RO membrane should last a year depending on your usuage. I just replaced mine last month and it was over a year.
With double or triple filtration befor the RO membrane, it the membrane is being past the water will seam better than raw water. That means taste is not a good measure.
A RO filter should remove most of the stuff from the water. I brought my conductivity meter home from work to test mine several years ago. Where as San Jose water runs about 500 to 800 micro mos the water from my RO system was 10 micro mos.
By the time you but all the filters and the RO membrane it may be 80% of the cost of a new system. So how good are you at changing parts? What kind of condition are the other parts of your system. Answer these questions to chose repairs or replacement.
I am not that familar with “under the sink home systems” as I primarily design industrial and municipal systems. As others have pointed out, in part, a RO system typically consists of the following components:
[ol]
[li]A pump to force the treated water through the membrane.[/li][li]A filter for removing suspended solids since the membranes get easily plugged.[/li][li]An activated carbon filter, or similar, for removing primarily residual chlorine which is not tolerated very well by the membranes.[/li][li]The RO cartridge or cartridges.[/li][li]A connection to discharge the reject waste from the system[/ol][/li]My first question to you would be whether or not the pump (sometimes called the permeate pump) is working properly and delivering satisfactory pressure? (BTW, if you don’t have a pump then you don’t have a RO system and most likely what you have is a filter for removing suspended solids which will not have any impact on dissolved solids). I would also check the reject stream, which on a home unit, I assume is connected into the drain pipe for the sink. Make sure it is not plugged. If you have very high hardness in your water it is possible that scaling could be occuring across the membranes and/or in the reject line
The first two above problems would likely result in no flow through the membrane (not enough differentiial pressure across the membrane). In this case it is possible that the system may have an internal bypass around the RO system that would simply route untreated water through to the faucet. You need to check the plumbing and system controls! For example, a high pressure switch on the reject line could open a bypass valve. The latter problems could be solved by chemically cleaning the membranes with an acid solution but I would definitely consult with the manufacturer before attempting this step.
BTW, the cartridges should last for at least several years if your influent filters (suspended solids and activated carbon) are working properly.
Several questions:
[ol]
[li]What is the hardness and total dissolved solids (TDS) or conductivity of your water?[/li][li]What is the manufacturer/model number information on your system?[/li][/ol]
I would imagine that this is a function of available water pressure? It appears from several vendor sites that if incoming pressure is less than 50 psig then a pump is required. Does your system have a bypass?