(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 9 of 9

Thread: Reverse Osmosis Distance

  1. #1

    Default Reverse Osmosis Distance

    Can anyone enlighten if 35-45 feet from our RO system to kitchen sink dispenser is to far? After filling up a 2 quart water jug the water pressure is reduced significantly.

    Short of moving the RO system is there anything I can do?

    The model is a Watts Flowmatic FMRO4G

    Thanks

  2. #2
    Master Plumber Redwood's Avatar
    Join Date
    Dec 2007
    Location
    Connecticut
    Posts
    7,463

    Default

    The distance doesn't help much BUT... Lets talk about Reverse Osmosis (RO)...
    Basically, In RO systems the water slowly seeps through the membrane. This membrane if I recall correctly is actually the outer lining of a pigs bladder. Does that water taste different now?
    Any way this membrane is so fine that that most of the contaminants in water are held back by this membrane. This membrane is washed clear by an almost continuable dribble of water to the drain so the membrane does not become clogged. The water that seeps through the membrane does so very slowly where it is then held in a small storage tank. When you pour off a large volume of water this storage tank is depleted and the pressure drops off until the storage can be replenished. Check the capacity for your unit and it may also help to spread the demand out over time. The piping is a long run and there is friction loss associated with it but I suspect your problem is much more the demand that you are placing on that old pig bladder!

    TMI?
    Last edited by Redwood; 06-23-2008 at 11:00 AM.

  3. #3
    Master Plumber master plumber mark's Avatar
    Join Date
    Feb 2005
    Location
    indianapolis indiana - land of the free, home of the brave....
    Posts
    4,243
    Blog Entries
    1

    Talking Ro Pump

    you can put a RO unit anywhere you want if you
    install a pump into the line....

    people have kitchens upstairs and downstairs and
    can put the Ro unit somewhere easily accessible in the mechanical rooom and run the poly lines to where-ever they want to


    they should be availabe from the local RO salesman.

  4. #4
    Plumber jimbo's Avatar
    Join Date
    Aug 2004
    Location
    San Diego
    Posts
    9,001

    Default

    Small undersink RO units are capable of producing a very small amount of water....possibly as little as 3 gallons per DAY. So taking 2 quarts all at once draws down the bladder tank.

  5. #5
    Master Plumber Redwood's Avatar
    Join Date
    Dec 2007
    Location
    Connecticut
    Posts
    7,463

    Default

    I finally looked this unit up at watt's site. It says that it has a capacity of 50 Gallons per day! However, the storage tank holds a maximum of 4 gallons. Now remember how tough I said it was for water to get through that pig bladder? The minimum pressure for this system is 30 PSI! Below that it won't do Jack! The maximum is 100 PSI. Mark is correct they do sell booster pumps for this unit and you do more than likely need one.

  6. #6
    In the Trades Bob NH's Avatar
    Join Date
    Oct 2005
    Location
    New Hampshire
    Posts
    3,307

    Default

    You can get a lot more storage if you add another bladder tank ANYWHERE and connect it at a tee off the existing line that delivers water from the RO system. I remmend that the new (additional, larger) tank be located near the point of maximum usage. Use at least 3/8" OD plastic tubing from the tank to the point of use.

    You should be able to use any tank that has stainless or plastic fittings. A tank from the RO company will probably cost 4 times as much.

    Precharge the tank to the lowest pressure that will reliably deliver water for your use (maybe 10 psi).

    The tank should fill to nearly system pressure overnight. Available drawdown should be around 50% of the tank volume.

  7. #7
    Master Plumber Redwood's Avatar
    Join Date
    Dec 2007
    Location
    Connecticut
    Posts
    7,463

    Default

    Stainless or plastic is a must...
    RO removes so much from the water that it becomes chemically a very hungry molecule... Copper will have a very short life expectancy with RO Water... Think of it as a solvent that dissolves copper!

  8. #8
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Location
    Cave Creek, Arizona
    Posts
    25,653

    Default ro

    The tank is a 5 gallon tank, but starts with the bladder completely filling the tank and 10 psi of air behind it. NO WATER will enter the tank until it reaches 10 psi and then the air pressure and the water pressure will be equal from then on, but the water has to compress the air volume to enter the tank. Therefore the water can NEVER completely fill the tank, and in most cases the air volume will be greater than the water volume. Your water pressure comes from the tank, not the RO unit, so taking 2 quarts of water from the tank AUTOMATICALLY reduces the pressure as the air volume increases and the pressure decreases. (For a given amount of air, volume and pressure are inversely related. Increase one and you decrease the other.) Your unit is working properly.

  9. #9
    Master Plumber Redwood's Avatar
    Join Date
    Dec 2007
    Location
    Connecticut
    Posts
    7,463

    Default

    Quote Originally Posted by Andy CWS View Post
    Are you saying that modern ROs are using pig bladders? Or are you referring to the French scientist that discovered the process in 1748 long before the invention of toilet paper. But of course, all in jest, right? Whew, you had me going there for a moment.

    I am not I get your understanding between total production per day and actual storage capacity.

    I am not familiar with any modern RO that continuously dribbles to the drain as automatic shut-offs are standard even with the el cheapo models. So the "windshield wiper effect" ceases when the tank is full. The contaminants in the water are given time to rest along side the membrane and a deterioration process can begin. That's why most manufacturers give a maximum one-year warranty on the membrane.

    I am not familiar with any home unit that holds 4 gallons. You can purchase upgrades of, say, a 7-gallon tank that can hold four gallons of draw-down water depending on the air pressure you set. Good luck getting that under the sink! [:-}
    Yea, Andy it was a joke! Thank goodness for a few advances in synthetics since the 1748 experiment so the synthetics were available for scientists developing the technology for the NASA Moon Missions. Did you have to google it? That RO water tastes better already!

    Those numbers came from the Watts page for that unit...
    Production of 50 GPD i would guess is a maximum capacity at the highest recommended pressure into a unrestricted container.
    The storage tank they supply with the unit they say has that capacity.
    So, 50 gallons per day maximum capacity into a storage tank of that size gives you what for capacity? Only whats available in the tank at the given time of use... Whats that? Who knows?

    As for the continous dribble down the drain with RO it takes a lot of "Dirty" water to make "Clean" water as the membrane is almost continiously washed while it is filtering.

    Scuuze me while I go get a good tall glass of OMG Horrors... Tap Water
    Last edited by Redwood; 07-12-2008 at 01:24 PM.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •