[Peter Rayner]

Hi I have done a service on my system 1 sediment and 2 carbon filters new resin. I have flushed the system out for 2 hours but cannot get the TDS below 65 before the  DI it starts high at 365 at the tap. Does it sound like the membrane is on its way out.

[SB Cleaning]

Yes afraid so

[simon w]

If there's no change in your taps TDS and your water pressure hasn't dropped significantly then yes it's probably your RO membrane. I've just had to change my 4040 membrane after two years use. My TDS is similar to yours and for three weeks I just couldn't get the water below 40 PPM . So I  bought a new one from June at Gaps and I'm now getting my water out in single figures again.