I don’t think that’s true? I thought when your membrane fails it fails big time? As in not just creeps up.
No, as the membrane ages, The output TDS starts to creep up. Pure production will slow, and resin use will increase. Knowing what your membrane outputs is key to knowing when it needs replaced.
My current ro produces 000 but I still DI anyway.
Good old Scottish water. Should be good with all the bloomin rain we get.