Conductivity of Demineralized Water

[Assuming the measuring units are μS/cm]

Is the RO equipment in good order as regards correct flows and pressures? - the membranes aren't fouled/blocked/damaged, are they? Are all the membrane interconnectors and vessel end-connectors in good order and not split/missing?

When was the last time the membranes had a manufacturer-recommended chemical clean procedure carried out on them?

Is whatever antiscalant dosing and pH correction that is fitted to the RO actually working correctly?

Is the mixed bed resin selection correct? Has one of the two resins needed actually been left out?

PWSlack covered alot.

One more thing that may help, what is the flux history on the R.O.

If you get the membreanes back flushed and washed, use knowledgable chemical people that know what they are doing, some chemicals (polymers for instance) react to some salts, and fouling your membranes beyond cleaning.

Please tell us size of equipment, membrane size, resin capacity, feed water characteristics, flow rates etc. Recently i faced a difficult situation in demin plant design and my post in CR4 helped a lot.

Please also check conductivity after RO and before resin bed, that will help you to decide whether the problem is with mixed bed or RO.

Just a moment,... you did not interchange concentrate and permeate tubings when you did the changes, did you? !!

dear jewel,i couldn't understand the purpose of D.M. plant after R.O. system;as R.O. system can remove upto 99% of T.D.S. even of size 0.0001 micron.Also you just can't use D.M. plant if you are using water for drinking purpose.you can use a water-distiller if want to use water for lab purpose.Distiller will give you much cheaper pure water than D.M. plant.you may be having higher conductivity of water as the final water may have residual caustic or Hcl. please cheque.