Reverse Osmosis Distance

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by peterd, Jun 23, 2008.

  1. peterd

    peterd New Member

    Messages:
    12
    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. Redwood

    Redwood Master Plumber

    Messages:
    7,453
    Location:
    Connecticut
    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.:eek: Does that water taste different now?:D
    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!:eek:

    TMI?
    Last edited: Jun 23, 2008
  3. 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. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    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. Redwood

    Redwood Master Plumber

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    Location:
    Connecticut
    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. Bob NH

    Bob NH In the Trades

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    Location:
    New Hampshire
    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. Redwood

    Redwood Master Plumber

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    Location:
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    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!:eek:
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,488
    Location:
    Cave Creek, Arizona
    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. Redwood

    Redwood Master Plumber

    Messages:
    7,453
    Location:
    Connecticut
    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!:D

    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:eek:
    Last edited: Jul 12, 2008
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