Sair, My First membrane did not last 18months.
It was supplied by facelift who used a Gapswater membrane.
I fear I made mistakes with the membrane which shortened its life. I moved it inside the house when I went on my hols in winter, I drained the water off which dried the membrane out, Plus I used cheap Carbon block filters which I left on for too long.
But I am pleased as punch with Ro mans membrane. 0tds, it cant get better then that, My 1000 ltr tank fills in 4 hours from empty.
Nel.