Well I don't 'backflush' but I do flush the membranes.
This may depend on the make, I don't know.
Mine is the small setup that Peter From Aquatec supplies with his systems.
I have the 200 gal per day one, this has the two smallish membranes that are set side by side above the 2 prefilters and the small DI column.
Flushing these membranes is a simple matter of popping out the tubes from the membranes that carry the waste water.
This in effect removes the flow restriction and when you turn on your tap the water just gushes straight out, flushing the membranes.
As it is only the work of a moment to do so, I now do this every few days, it only takes a few minutes.
Regards,
Ian