RO Water System For Home Use

redfishbluefish · Apr 8, 2016

I have a spare RO unit and was kicking around the idea of hooking it up to my kitchen sink and using it for drinking water and making ice. We currently use quite a bit of bottled water, and our ice maker is using untreated tap water. However, with my knowledge I've gained from my "fish" RO/DI unit, I'm scratching my head as to if it's worth it. Home units typically have a three gallon reservoir, so the unit doesn't have to run every time you use water. With my fish unit, on start up, I have break-through TDS, shooting up to maybe 60 or so TDS, and then slowly coming down over the next four to five minutes. For the fish, I have a tee valve and run this startup water to waste. For the home use unit, this start-up breakthrough will be going right into the reservoir. I don't know how frequently the unit will need to refill the reservoir, but I've got to believe it only takes a gallon or so before it refills. I'm now wondering, with only a three gallon reservoir, what kind of TDS I'll find coming out of the RO faucet.

The other issue is that we don't have the greatest water pressure. I'm high in elevation within the town, and the water supply reservoir is very close to my house. I originally didn't use a pressure pump for my fish unit (maybe the first year of use), and water production was slow. I don't care about it being slow for the home use unit, but wonder what that will do to performance.

Last time I tested my raw water, the TDS was 240-250. Once my fish unit is running for ten minutes or so, in the winter, RO is producing 0 TDS, while summer, 2 TDS, before going through DI.

I would need to purchase the reservoir tank, RO faucet and whatever else I might need to hook this thing up.

So is it worth it? What kind of TDS should I expect out of the RO faucet?

TheEngineer · Apr 8, 2016

Even with higher than zero TDS it is still "better" than your raw tap water. Is there anything in your water you don't want to be drinking?

AZDesertRat · Apr 8, 2016

You will see the effects of TDS creep in the pressure tank but one way to help this is to completely drain the pressure tank maybe once every week or two and let it refill completely in a single long run. You might check out purelyh2o for the add on drinking water kit, they are only $60 complete with everything you need.

Your expected TDS will depend on the efficiency or rejection rate of the RO membrane for the most part and how you use the pressurized water. If you fill something like plastic Gatorade type bottles or pitchers the TDS creep will be minimal as it takes longer to recover. If you are filling a 6 oz glass frequently the TDS creep will be more apparent as the RO will short cycle more often.
Its still better than tap as long as you maintain the system and filters and do at least an annual disinfection of the entire system.

dvbrien · Apr 8, 2016

Or you can run a tds bypass on the "home unit". And buy a type s membrane... Note: there have been a lot of debate about drinking DI water. Being that di is void of anything it will act as a solvent and strip things it contacts... but I've never had that experience. I love DI ice it does crazy looking things. Like mountain peaks in the middle of the cube. Great for brandy!

LostInTheDark · Apr 8, 2016

Paul,

I have a setup similar to what you are describing. I run a Typhoon III Extreme that is "T"'d off to a pressure tank to hold RO water going to the fridge. Its one of the best perks of having the unit besides the pure RO/DI water. I use a booster pump that takes my water pressure from about 45 to 65 psi. Its "T"'d off to a permeate pump which helps against the back pressure of the holding tank. I use both a 3.5 and 13 gallon tank in series and the water runs through a carbon filter and into the fridge. My TDS into and out of the tank is usually about 2 or 3. Its 1 going into the DI units.
The water is like night and day from regular tap water. I used to live in Manhattan where the water is probably the best in the US. I could never get used to the taste of NJ water. I found the 3.5 gallon tank too small as the pumps would turn on a few times a day. With the 16 gallons I have now it runs maybe once a day. I have very little TDS creep because the unit is used daily and never gets a chance to accumulate any impurities. With all the news about lead and such in the drinking water it does lend to piece of mind also.