RO/DI unit with well water? RO/DI water to waste water ratio?

[jacksparrow7]

Aloha all, I am really looking into buying a RO/DI unit, acutally sick of spilling water on the floor, anyway, I am on a well and if I'm reading the research right that you need at least 60psi at the faucet to get the best pressure through the RO/DI unit for the best results. I was told I also need a booster pump to achieve this and I was told in the fall and winter time the well water water will be very cold so I should expect a huge drop in water production. Is this all true? My second question is there any units that have a good RO/DI water to waste water ratio? Having a well run dry is not going to go over well with the wife.
Mahalo All
Jack

[sjj80]

I'm also looking for an RO/DI system and I also have well water. I've heard spectrapure maxcap is good but they're a little too pricey. I've also heard that the filter guys were good as well, and on their website they give reccommendations for filters to use on well water. I'm planning on calling them and seeing what they reccommend, cause my husband wouldn't appreciate me running the well dry either, lol.

[AZDesertRat]

Dow Filmtec RO membranes get their production rating at 50 psi and 77 degrees F. If you have more or less of either it does affect output.
Look over on the Buckeye Field Supply Sponsors Forum for a really neat calculator Russ has put together that shows you what to expect if you have an idea of what your temp and pressure might be.
There are units today that have somewhat lower waste ratios but most of them require higher pressures to drive water through the second membrane and most will have shortened membrane life due to the lower waste ratio.
Spectrapure units are more expensive but they are far superior to others so the additional cost is easily justified when you consider the extended membrane and DI life they give you. They also offer a dual membrane lower waste unit which might fit your application. They even have a unit coming out soon that will only waste 1:1 unlike the standard 4:1 and will be microprocessor controlled for optimal control, superior water quality and maximim filter life.

[jacksparrow7]

Mahalo AZDesertRat, I have read most of your posts and knew you would have a answer for me. The 1:1 unit is coming out soon is straight up my alley but would I still need a booster pump to achieve optimum performance or would this 1:1 unit be able to run at the 50psi previously mentioned? I need to grab a pressure gauge to measure my pressure at the basement spiket but I do know I have 30gal a minute coming out because when the sprinkler system was put in, I blew off 8 sprinkler heads and the installer had install reducers to lower the pressure at the heads. The well is 648' down and I had the EPA (my sister is a director there) test the water and other than the Iron being slightly elevated, it's perfect as spring water. So I will be checking the Spectrapure website daily for that unit.
Mahalo again
Jack

[Deep6]

I have well water and use an ro/di filter I got from e-bay:

http://stores.ebay.com/The-Aqua-Safe...Q3amesstQQtZkm

My well water is cold and my pressure is about 45 lbs. It works fine You can ajust your pressure where the guage is on the blue tank where it comes into the house by a screw in the little box next to the pressure gauge. Anyway at 45 lbs with cold water mine is working with no problems. You can get a 6 stage ro/di unit from the link above for less than $150 shipped with the holding tank and fauset.

[AZDesertRat]

But the quality is not even in the same ballpark nor will it give you 1:1 waste ratio or better.
I see posts all the time recommending e-bay units but rarely do any of the posters list their actual numbers and filter life. Tell us your tap water TDS, RO only TDS without DI and RO/DI TDS and how long the DI resin lasts. The quality just doesn't compare.
I will gladly post my TDS numbers from just last night.
Tap Water TDS is 852, RO only without DI is 6.4 for a RO rejection rate of 99.25% which is way higher than a normal RO membrane delivers. Pressure was 58 psi and temperature was 69 degrees. My RO/DI TDS is so much lower than an indicated 0 TDS it has to be measured with a conductivity or resistivity meter still and thats after 545 gallons of DI through the same cartridge and its still going strong. My unit is a Spectrapure 90 GPD MaxCap RO/DI system that is over 8 months old now and sees heavy usage for drinking water, icemaker and reef uses.

[Deep6]

My unit is over two years old now and I replaced the filters at the one year point. I use the thing like crazy for the fish tank, cooking, coffee and drinking water. My fish tank alone uses more than 500 gal. per year (just evaporation) without water changes and then add the coffee, drinking water and cooking. My TDS reading is at a constant 1 with the di, even just before changing the filters and di resin. My well is only 85' deep and loaded with iron. My reading before the Ro/di is about 600. And last but not least my fish tank is very happy using that filtered water. I have had no deaths, and the water is perfect. So I guess at the end of the day it works!

[Deep6]

Oh and I forgot to mention that the $250 savings you will have not buying a Spectrapure 90 GPD MaxCap RO/DI at $400. You can replace your filters every year for the next three years and still have enough left over for a new fish.

[AZDesertRat]

You conviently forgot to tell us the RO only TDS. Thats the true measure of an RO/DI system. I can run water through a cheap Tap Water Filter and get 0 TDS, for a little while anyway. Any unit on the market should be capable of 0 TDS, the key is for how long and how long the components last in the process. Again do some research and you will find there is no comparison.

[jeeperrs]

I bought a 75 gallon compact version through a place called air, water, and ice. I can't report the psi because I did not buy a pressure gage but I can tell you my tap water was 600 TDS (not sure of the temp but it is lower than 77 because my tap water runs very cold). I bought a RO only valve for 9 bucks and my RO only is at 15. This is not equal to the 6 but I don't think 9 TDS warrants the almost $300 price difference. When DI is on it is at 0 TDS which I guess is expected. The only thing that would be great is a better ratio of filtered water verses waste water. I would take price into consideration because when you get down to it what is the difference between 1 or 2 TDS if it is going to cost 2 or 3 times more money.

[Deep6]

Why do you run the unit without the di? That is irrelevant, as they all work together. I have never in two years ever run the unit on the ro by itself. I makes no since. The bottom line is, what the unit produces, in the way it was designed to produce it. It was designed to produce water with the ro and di working together. And to answer to your question no, I have never tested it with the di on the side, because it is always working in line with the ro. That is not the way anyone would every use an ro/di unit. Who would have a filter that has ro and di and run it without the di? Once again at the end of the day, using the system the way it was designed to be used, what is the end result for the money spent? You can spend $400 for a unit that puts out 90 gal per day of water that tests at 0 tds or a unit at 100 gal per day for $150 that puts out water at 1 tds (negligible difference) and pocket the change. I still fail to see your point. I’m sure you’re trying to justify the difference in price but, it doesn’t seem to have a lot of numbers behind it to back you up.

[Deep6]

Oh I forgot to answer the last part about a cheep water filter producing a 0 tds for a short time only. Keep in mind I only changed my filters after one year because that was the recommended time to do so, and still the tds rating was at 1 before changing them.

[AZDesertRat]

The key is, for every 2% you increase the RO membrane efficiency you DOUBLE the DI resin life. This can add up very quickly if you have very high TDS to begin with. If your water is pretty good to begin with it takes a little longer to recoup the cost difference. Another key point is with the quality of prefilters and carbons they use the RO membranes almost never wear out. Randy Holmes Farley recently posted a thread where he has just replaced his Spectrapure membrane after just short of 10 YEARS use. The average membrane lasts less than 3 years and in Phoenix its more like 18 to 24 months.
Add those savings up and the math shows the average user recovers the cost difference in about 1 year and if your water is better than average its still less than 2 years. I plan to keep it for over 10 years just like I did my last RO/DI unit so it will continue to save me money for its entire life.

An how do you figure RO numbers are irrelevant? Have you ever even tested it or bothered to see how well its working. You might be surprised at how long you can make DI last if you increase the efficiency of your unit. I have proof it works and is still working on the first DI cartridge still. The difference between 150 gallons of DI water and now over 545 gallons and still going strong is not significant to you. Do you think DI resin grows on trees and is free for the taking? Or that RO membranes are free for the asking?

I use my RO every day for drinking water and ice as well as other pet watering and cooking so RO is a very important part of the process.

Do you have any idea what that 1 TDS is? TDS is an equation and not a true number and you have no idea at all what it is made up of, in fact some contaminants are not detected by a normal TDS meter so you want the best filtration you can buy to ensure you are not filling your tank with phosphates or silicates.

[Dholmblad]

Sorry for taking over but.. How often should you replace filters? And is it bad if I have not....

[Deep6]

Dude, you didn't answer the question. Why do you use the ro with out the di? All the stuff you wrote is a very nice story but, once again, at the end of the day 0 tds and 1 tds is a negligible difference to justify a $250 difference in price. The filter changes are once a year no matter what filter you have, that is that. Give me a real reason why to spend $400 over $150. My tank is happy, my coffee is happy, my cooking is happy and my wallet is happy. You can quote me all kinds of studies, and my system is still working like a charm for less.

[AZDesertRat]

Prefilters and carbons should be replaced every 6 months. At the same time you do this you should disinfect the filter housings with a bleach solution. Both of these measures are to help prevent any bacteria or virus growth inside the unit as well as to protect the membrane and make it function better.
Inexpensive granular activated carbon filters are only good for 200 to 300 gallons of normally chlorinated tap water at 1 mg/L residual. Higher quality 0.5 micron solid carbon blocks are rated for 20,000 gallons at the same residual so it pays to buy the best you can. TFC RO membranes cannot tolerate chlorine or they literally melt. Same goes with prefilters. Most prefilters on the market are what is called nominal rated filters meaning they only have to trap a small percentage of sediment or particulates at their rated size to be sold at that rating. Better prefilters are what is called absolute rated meaning they trap everything from their rated micron size and larger. This is important to protect both your downstream carbon block and your RO membrane.

Membranes should go at least 2 to 3 years and longer if you use good quality pre and carbon filters and do thw required maintenance. DI resin should be changed when you see anything other than a consistent 0 TDS and certainly at no higher than 2 or 3.

[AZDesertRat]

I answered your question very plainly. Drinking water and ice etc, it doesn't get much plainer than that does it?
You think your unit is working but you have no numbers to back up your claims. I keep a log book and can tell you for a fact every gallon of DI water I have produced since day one.
You are fighting a losing battle here and will not win.

You also are misquoting prices, the MaxCap RO/DI is only $349 in the 90 GPD version, $369 in the 150 GPD version and $429 in the 300 GPD version and those are retail prices. They sponsor group buys and units can be had for less than that as many here can testify.

[Deep6]

Once again I read your post and it is right on the money, all those stats are great information. I agree the unit you bought is top of the line but, it does not produce anything but a negligible difference to mine. I still don't get the sales pitch and still don't get why you would run the ro without the di?

[AZDesertRat]

I'm done, you are wasting everyones time here.

[Deep6]

My only point here was that you don't have to spend a king’s ransom to get something that works.

[Deep6]

Oh I forgot to mention that might not be waiting everyone’s time!

[kbohip]

Hey Deep6 thanks for the link to the R/O system. It's just what I need, and as a bonus, I can afford it!

[Deep6]

Well what can I tell you, Sorry for the confrontation but, the thing works.