RO Restrictor question

Question:

chaps what is the purpose of the flow restrictor?

I'm trying to run my RO unit in a mains pressurised system. Mine never goes to a fully closed position (nor does the one in the shop where I bought mine from). This means that it is always leaking waste water even when no RO water is being produced.

So is this the way things were meant to be?

It seems to me that the constant leak both wastes water *and* reduces the differential pressure across the membrane thereby reducing the efficiency of the unit.

If this is meant to be a shut off valve and meant to remain shut off unless purging the system, could I have one that works properly, either >that or two 3/4" BSP to 6mm pipe adapters that i might fit my own shut-off/restrictor valve.

Roc