RO/DI Operating Cost???

G

guntercb

New member
Can anyone with a RO/DI unit share their operating cost ? I am thinking of purchasing a RO/DI unit and and wondering what it actually cost to operate one of these units. Can anyone let me know what they spend on membranes/ filters? How often do you buy them or better yet how many gallons of water do you estimate you can make before you need to replace them? What do you spend on DI resin? How many gallons will this allow you to make and keep your TDS at a level you like? What TDS do you try to maintain?

Any information would be greatly appreciated. I tried to search google for any information, but could find nothing.

Thanks in advanced.

Cheers,
Chris
 
I have a bare bones RO unit for about 6 or 8 years. I only changed the membrane once. It costs about $30.00 for the membrane. The carbon and prefilters are about $14.00 depending on the quality. The entire unit was not that much but I forgot how much maybe $50.00. So I spent about $1.00 a month so far. My unit makes 15 gallons a day. It is free to operate.
Paul
 
Chris,
I go through anywhere from 150-300 gallons a week, or about 600-1200 gallons per month.

I get about a month or so usually on my pre-filters and DI and thats using it almost everyday at least 12 hours a day. I guage my changes by using an in-line TDS meter and typically change when I hit three TDS.

I buy my prefilters (carbon and sediment) each in ten packs which cuts the cost down.

Monthly operating cost including water charges has to be around 25 bucks. I'm sure you would spend far less than that though considering that you probably wont use more than 20 gallons on an averege week at the most.
 
Paul B,

Thanks for the response.

NorthTampaTang,

Thanks for the detail you supply. You are right, I don't imagine my RO/DI use will ever reach 20 gallons a week. (-: I will use the numbers you give me to base some rough calculations on. Roughly how often do you have to have to change your RO membrane?

PelagicMagic,

I read your thread. Thanks for attaching it. And you can use your well water to run through your RO/Unit. Just be sure you have the pressure to operate your RO unit. Normally you will have a hydrostatic tank after your well pump to keep steady pressure. Also, you might actually be better to use the well water because you will not have the chlorimines to content with. Just a note - much of the drinking water in Florida comes directly from wells were pretty much the only treatiment is adding Chlorine or Chlromines.

Can anyone else supply my with some data that I can construct a cost of operating an RO/DI unit?

Thanks,
Chris
 
You can usually get 3+ years on a membraine, depending on how well your pre-filters work. Ive been using my spectrapure membraine for over 3 years with no noticable drop in efficiency
 
I go the aquamaxx. Filter change for 3 filters is 19.95 and the membrane is 30 bucks. I didnt know I could get that much life out of the membrane. Another good thing to have is a TDS meter
 
i run a typoonIII RO/DI. I go through approx 80-100 gallons per month. my water bill changed very little. not enough to really notice thats for sure.

here is a break down. now keep in mind this is for stpete so your water charges may be a bit more or less depending on location. not enough difference to mater.

water cost you

1.01 per 1000 gallons up to 5600 gallons
1.67 per 1000 gallons for the next 2400 gallons
2.86 per 1000 gallons for the next 7000 gallons

then you have the sewage/waste water charge of 1.64 per 1000 gallons

then you have the tampa water authority charge of 3.37 per 1000 gallons

so cost per gallon= 1.01+1.64+3.37/1000gallons=.01 per gallon.
This assumes you use less then 5600 gallons per month. adjust accordingly.

now take that to figure out cost of using the unit.
this is a first year cost. The cost goes down in the second year because you dont have the added expense of the unit purchase.

ro/di unit 200.00
per gallon cost $0.01x400 gallons x 12 months= $48.00 assuming the average 3 to 1 waste
Salt=$45.00 per 160 gallon bucket x7.50 buckets=$337.50
lets say you change the filters twice<--overkill at only 100 per month= 50.00x2= 100.00

total first year cost= 685.00

your per gallon cost is .04 cents fresh
.32 cents salt

This figures you use 100 gallons per month with half that being salt and the rest for top off

total cost of buying it at the store per year=1200.00 fresh
1800.00 salt

this assumes the average cost of the store water from the area

so i said all that to say this. it is alot cheaper to do it youself with the added benifit of knowing the quality of the water since you made it yourself
 
Oceana, I have the typhoon III as well, where are you getting your filters? and did you notice that the DI filter is a cartrage that the bottom will come off to change out the resin? I am still getting my filters from airwaterice.com at 49.95 a set (all filters) and I am changing them out about every 6 months.
 
i also get them from airwater ice. i just rounded up to 50.00 per set.

i have not changed them yet. had it for around 6 months and still at 0 tds with the new propagation system and orders however i am going through ALOT more water then i was so i expect to be changing them alot more then in the past. as far as i know the only reason to change them is if your TDS is going up and your production is going down.
 
Oceana,

Thanks for the added info. I think I need to get an RO/DI unit ASAP. It appears to have a quick return on investiment. Thanks for the detail you provided.

I was checking out the airwaterice web site and it looks like the DI vertical DI unit will take out a total of 6,800 ppm. So take your TDM output from the RO unit and divide it into 6,800 and you will have an idea of how many gallons you can make before changing the DI. But I think just monitoring the DI will be easier.

I calculated I spend about 160 dollars a year buying water and if I get an RO/DI I will spend about 73 dollars a year on filters and DI resin and the water along with the wasted water. So I will save 87 bucks a year which will soon pay for the unit.

I see a RO/DI unit in my future. Oceana and Dave, how do you like the Tyhoon Unit?

Cheers,
Chris
 
i love it. IMO for the money it cant be beat. oTDS everytime. simple to use. super good customer service. nice solid unit. easy to install. your welcome to come see mine before you buy one if ya want
 
well actually it can be beat or at least matched. john builds them and has good prices on replacement filters. I buy wholesale so I get them cheaper for myself. I posted a thread asking if anyone wanted to go in on a bulk order and also had the club president ask at a meeting if anyone wanted to go in on a bulk order I would not have made a dime on and everyone said they would rather pay more money for some reason. so after that john has good local prices. you can also buy small bags of the best resin for our use from him at a decent price. he is buying the best not the cheapest.
also some people seem to believe filters are never ending. when you get a pressure drop of approximately 2 lb. your sediment needs changed and you should run at least a 1 micron and when you test chlorine after your carbon and get a reading you should change your carbon. ro membranes pull a percentage and when you install the ro you should calculate the percentage removed and when it changes you should change the membrane. knowing the tds after the membrane is a must in my opinion and when it goes up you should change the membrane because if you don't it will use the di resin alot faster and since gallon for gallon the resin is the most expensive part of the system. saying something will pull out so many ppm tds is kind of off when it comes to our use since everyone fills there membranes differently and if you do it not so perfect it will not last as long and there also won't be as much in the canister to filter in the first place.
chris I think it is a very good idea for you to get an ro/di unit. I personally think everyone should have it for drinking water if nothing else but that is just me. if you drink the di water alot of people like to run another carbon after it to remove the taste given by the resin byproducts. I personally don't like drinking city ammonia water so I use mine for alot more than just the tank. my water bill is through the roof at $148 for 2 months. I am going to have to cut back somewhere.
 
understand I wasn't trying to emply that I sell anything at all just incase a moderator thinks so. what I was going to do was not going to make me a dime.
a hand held digital tds meter like a hanna tds 1 is a good idea to have just to make sure the little push button is still working I have seen them set for less than one and still not go red at over 20 ppm tds. nothing in this world is perfect
 
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