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Reverse Osmosis Water Filter
Old 10-29-2007, 09:51 AM   #1
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Reverse Osmosis Water Filter

Does anyone have a handle on how often to service these? Mine has two filters and the membrane cartridge. It works perfectly now but I'm trying to get a feel for the downside if I don't replace the (expensive) filters on a regular basis. Does the filter just quit giving adequate filtered water quantity or does something dire happen?

The manual says to replace filters every 6 months , no guidance on the membrane replacement interval. Thanks.
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Old 10-29-2007, 12:46 PM   #2
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I know that the membranes are backflushed periodically by the RO filter itself. It may be designed to last the life of the unit. I have no idea.

-CC
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Old 10-29-2007, 01:09 PM   #3
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Does anyone have a handle on how often to service these? Mine has two filters and the membrane cartridge. It works perfectly now but I'm trying to get a feel for the downside if I don't replace the (expensive) filters on a regular basis. Does the filter just quit giving adequate filtered water quantity or does something dire happen?
The manual says to replace filters every 6 months , no guidance on the membrane replacement interval. Thanks.
That's an interesting question. The less-biased sites that I usually check for system & repair info (fixitnow.com & dulley.com) don't have anything about RO systems. However there's a whole bunch of manufacturer's sites insisting that you have to replace the membrane every 2-3 years or your family will suffer horrible genetic mutations before dying painfully possibly experience reduced water quality.

Here's a different question-- is a RO system the best for your needs? They waste water at something like a 3:1 ratio and depending on your water use you may be paying a lot of utility bills for the privilege. Meanwhile a whole-house water conditioner goes through a $7 bag of salt every 4-6 weeks and maybe 20 gallons per weekly flush. And a carbon/mechanical filter may catch everything you care about for even less money. Your chosen system depends on the Love Canal water-supply challenges in your area. Even RO systems may still let bacteria and some pesticides through, and the only solution for that problem may be boiling/distillation. But if you just have a bunch of minerals & iron in your well then water conditioners or carbon filters can do the job for a lot less money.

As I was retiring in 2002, the Navy was testing shipboard RO water-purification systems. Running an evaporator is a tremendous investment in time & repair parts and an electric vapor distiller is a colossal PITA to keep running. Meanwhile RO systems just keep chugging away with little supervision and nobody cares about wasting seawater. The Army does the same thing with water buffalos from impure sources like streams or swamps. Even with memranes & filter replacements it's probably cheaper than distilling it or trucking it in.

Telly? What's your experience?
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Old 10-29-2007, 01:51 PM   #4
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........Here's a different question-- is a RO system the best for your needs? They waste water at something like a 3:1 ratio and depending on your water use you may be paying a lot of utility bills for the privilege. Meanwhile a whole-house water conditioner goes through a $7 bag of salt every 4-6 weeks and maybe 20 gallons per weekly flush. And a carbon/mechanical filter may catch everything you care about for even less money. Your chosen system depends on the Love Canal water-supply challenges in your area. Even RO systems may still let bacteria and some pesticides through, and the only solution for that problem may be boiling/distillation. But if you just have a bunch of minerals & iron in your well then water conditioners or carbon filters can do the job for a lot less money.......
Thanks for the response. I use at most 2 gallons of treated water a day - so I'm wasting maybe a couple of toilet flushes worth of water per day. I am on a well and the water is hard, so I treat the rest of the household water with a traditional water softener. The tap to the RO system uses the softener, per the installation instructions.

I tried the charcoal system and it didn't pass DW's sniff test.
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Old 10-29-2007, 01:55 PM   #5
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The membrane should last at least 4-5 years. The prefilters should definitely be replaced on schedule per the number of gallons of water filtered rather than a fixed monthly schedule, but I'd replace them yearly. Bacteria can be a serious issue, along with metallic contamination.

Some water just cant be treated without RO. Our old house initially used well water that had variable nitrates and arsenic levels, so we drank bottled water but many neighbors used RO. The RO water tasted awful so I never put in a system. A year later the city put in a connection to the river sourced city water, so that solved that problem.

Newer RO systems are more efficient than older ones, and some are nearly 'waste free'.
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Old 10-29-2007, 02:21 PM   #6
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Travelover,

I'm on a well also, with very hard water (34 grains/gal). I installed a water softener to reduce the hardness for all the water in the house (except an outside house bib). My drinking water goes through two sediment filters (30 micron and 5 micron), and the RO canister. Then, through a small "finishing filter" of activated charcoal. Final step: a small UV light that kills any bugs. This drinking water system is plumbed to a separate tap at our kitchen sink and to the icemaker in the freezer.

As you probably know, your water softener adds sodium (or potassium, if you use a salt substitute) at a rate proportional to your original water hardness. So, if you have really hard well water, your drinking water will end up with a lot of salt in it unless you remove it. The only practical ways to remove it are with an RO system or by distillation.

Distillation: Unless you want to mass with a "batch" system that makes a gallon or two at a time, distillation equipment is pricey. Also, the electric costs over time are considerable. And, there's maintenance of the equipment . I wanted the convenience of a tap at my sink and a functioning icemaker, so I went with RO.

Back to your original question: I've read that the RO membrane needs to be replaced every 2-3 years, but like you I don't know how you'd tell if it wasn't working. I figure one of two things might happen: either the water volume will decrease (i.e. clogged up membrane) or the water quality will decline (i.e. membrane degradation). I can see if the water quantity has declined, so I'm not worried about that. For about 20 bucks you can get an electronic tester that tells you the amount of dissolved solids in your water (they even make sink taps with this gizmo built in). If your RO membrane goes bad, your dissolved solids would go up (since the salt from your water softener would get through) and you'd know to change your RO membrane. If this testing allows you to get another year out of your membrane, then it has paid for itself.

Other notes:
- If you get an RO unit, consider getting a "permeate pump" too. It costs about $100 more (IIRC), but it will dramatically reduce the water waste of an RO unit, especially if your water pressure isn't high to start with. Remember, even f you are on a well, you pay for electricity to pump that water and getting rid of it costs money if you are on city sewer or loads up your septic system.
- The UV light unit costs about $30 for a replacement bulb I'm going to cut that cost by 75% by fabricating my own holder next year) plus a few buck in electricity. It kills just about every type of bacteria or virus. We had some coliform bacteria in the well when we moved in, and I knocked it out with bleach. Still, I didn't want to worry about it anymore, ad this has been cheap insurance.
- I'd recommend you get a comprehensive water test if you haven't already. There's nasty stuff in some places, and when you have a well the entire responsibility for dealing with it is on you.


I did all my installation myself, and the drinking water system (3 filter cannisters (2x sediment plus the ability to fit a charcoal filter later), RO membrane with pressure tank, permeate pump, polishing filter, UV light) ended up costing me $340 (in Jul 2005).

samclem
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Old 10-29-2007, 02:44 PM   #7
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samclem, I feel your pain. Our well water runs 75+ grains of hardness and we use a water softener to take the edge off, but stopped there. We buy drinking water for $0.25/gal in refillable 3 gallon bottles. 5 bottles lasts about 2 weeks and the minor inconvenience of refilling them is worth it (call me El Cheapo ) compared to the cost of filters and a RO system.
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Old 10-29-2007, 05:04 PM   #8
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Agree with samclem. We are also on a hard water well, so water has high sodium from the softener. We RO for some drinking water, making coffee, and for most of my beer brewing (add minerals as needed is easier when starting with a blank slate).

The one I bought is meant for people with fish tanks. No pressure tank, I just let it fill a big jug, and I fill gallon jugs from that as needed. It is supposedly more efficient when it is not fighting the back pressure from the pressure container. I rigged up a timer for it, it runs long enough to fill the jug.

I've had it about 10 years. IIRC, the guy said the RO membrane should last at least 10 years. Mine has one charcoal filter in front of it, I also put a 'screen' type filter before that. They recc replacing the filters and cleaning the unit out every 3-6 months. You can get bacteria build up in the charcoal under certain conditions. Mine would get a nasty rotten egg sulfur smell - time to change the charcoal, and mildly bleach the canisters. Sometimes that would happen in three months, other times I think I went a year and didn't notice anything off, but changed it 'just in case'.


RO water has no minerals and probably no oxygen, so it is bland tasting. Family is used to it, I often drink our high solids well water straight - I grew up on hard water, tastes fine to me. But way too much minerals and iron for beer making.

Did you say the RO would bypass the water softner? That goes against what I've read, and what I've done. RO the softened water, and about all the RO unit has to do it take out the salt. I think that is why mine has lasted so long.

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Old 10-29-2007, 06:30 PM   #9
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..................Did you say the RO would bypass the water softner? That goes against what I've read, and what I've done. RO the softened water, and about all the RO unit has to do it take out the salt. I think that is why mine has lasted so long.-ERD50
Yes, I wrote that, but I was remembering incorrectly. It does use softened water as a source.


Thanks to all that have replied. I think I'll change the filters, do the recommended bleach routine and see if I can find a test lab to check my well water quality. I haven't bleached it in about 10 years.
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Old 10-29-2007, 06:36 PM   #10
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Just be careful with the bleach. IIRC, some membranes are very sensitive to chlorine and will burn through. I always keep the membrane away from the bleach and rinse everything well before reassembling.

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Old 10-29-2007, 06:56 PM   #11
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Just be careful with the bleach. IIRC, some membranes are very sensitive to chlorine and will burn through. I always keep the membrane away from the bleach and rinse everything well before reassembling.

-ERD50

Thanks for the reminder. The instructions actually suggest a mild bleach solution when changing the filters, but there is a sequencing of operations to protect the membrane.
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Old 10-29-2007, 08:25 PM   #12
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I think I'll change the filters, do the recommended bleach routine and see if I can find a test lab to check my well water quality. I haven't bleached it in about 10 years.
This is the company that tested my water. I don't know if the price is the lowest you could find, but their service was good and they've been in business for awhile.
Water Testing by a Professional Water Test Laboratory
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Old 10-29-2007, 10:02 PM   #13
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Water testing labs: This one comes highly recc from people on the beer brewing forum. Beer is ~ 95% water, pretty important stuff, and the chemical analysis affects the process.


Ward Laboratories, Agricultural Testing, Consulting, Kearney, Nebraska


I've never used them, don't know how they compare with the one samclem provided, just another option.

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Old 10-30-2007, 09:16 AM   #14
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Thanks for the recommendations. I'll see if I can FAX them a water sample.
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Old 10-31-2007, 12:04 PM   #15
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I just installed a Watts R-O system (around $169 from Costco). Like most others, it has a set of filters that should be changed every 6 months, and I think it's already been mentioned that you want to change those so you don't get a bacteria colony growing on the collected sediment.

The membrane doesn't have a set schedule. The manufacturer recommends you test your water with a TDS (Total Dissolved Solids) meter, and replace the membrane when your system is no longer removing 80% of the TDS.

I bought a Hanna "TDS-EZ" meter on Ebay for around $16. It shows our tap water is pretty good at about 190 ppm TDS, and the R-O system currently takes that down to about 15 ppm. My personal taste-meter suggests that the R-O system is definitely getting rid of something unpleasant in the tap water, but I suspect that has little to do with the TDS.

Membranes aren't cheap so I like the idea of using the meter to make certain it needs to be replaced before spending the money.
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Old 10-31-2007, 12:15 PM   #16
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Thanks, SC, I'll check it out.
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Old 10-31-2007, 12:26 PM   #17
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Thanks for the recommendations. I'll see if I can FAX them a water sample.
FAXing is so 1980's. Just email them a sample

SC - I didn't know the TDS testers were that cheap. Maybe I'll pick one up. I figured I'd tell if it failed just by the flow rates or taste. Humans can detect some stuff in the ppB range, which is pretty amazing.

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Old 10-31-2007, 01:52 PM   #18
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As an aside, I found some interesting water testing stuff in the aquarium section of the pet store, and most of it was a lot cheaper than the official "human water testing" stuff at the hardware store. I wouldnt trust it for accurate PPM levels, but to test for the simple presence of something like arsenic or nitrates, its an inexpensive alternative.
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Old 10-31-2007, 04:19 PM   #19
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As an aside, I found some interesting water testing stuff in the aquarium section of the pet store, and most of it was a lot cheaper than the official "human water testing" stuff at the hardware store. I wouldnt trust it for accurate PPM levels, but to test for the simple presence of something like arsenic or nitrates, its an inexpensive alternative.
Heck I've been buying my medications at the farm supply for years........
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Old 10-31-2007, 08:06 PM   #20
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Hey, whats a few horse tranquilizers between friends
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