Hot Water~ the water temperature must be below 80 degrees F or 26 C also Freezing will destroy a membrane.
Chlorine~ A small amount of Chlorine WILL dissolve/melt your membrane. You must assure there is no chlorine in the water after your carbon. Standard Carbons should be changed when your unit has produced 3000 total gallons INCLUDE both the Product and WASTE/concentrate streams in your total calculation
Insufficient concentrate~ you can run your membrane so that it produces less waste BUT you WILL shorten the life of your membrane.