Testing a ro membrane

[riche]

Is there a way to test the ro membrane?

I know they say there usually good for 3 year and if you flush them even longer.

 

[AZDesertRat]

You use your handheld TDS meter to test the tap water TDS and the RO only TDS then use those two numbers to calculate the rejection rate or removal efficiency.
An example would be say your tap TDS is 250 and your RO only TDS before the DI is 10. The formula is tap TDS - RO TDS, divided by the original tap TDS then multiplied by 100. 250-10 = 240, 240/250 = 0.96, 0.96x100 = 96% rejection rate which would be on the lower end of membrane efficiency, you want to be in the 98% range or higher for best DI life.

Membrane life is dependent on several things, soft water or hard water, tap TDS, your waste ratio, the quality, micron range and how well you maintain your sediment and carbon block filters, water temperature, water pressure and how you make your water.

Membranes love soft water, it greatly extends their life as the softener does much of the work ahead of time so the membrane does not work as hard. Good sediment and carbon filters protect the membrane from silt, particulates, colloidal material and chlorine so play a huge role in membrane life. Keeping the waste ratio at 3:1 to 4:1 depending on your hardness and tap TDS is critical, flush kits do nothing but lighten your wallet. Colder water actually treats better than warmer water so never try to raise the temperature by adding hot water. The higher the pressure the more efficient the membrane becomes and the better it can rid itself of wastes. Making water in small batches is hard on a membrane as again it does not have time to cleanse itself.

My personal RO membrane is 9 years old and as good as the day I bought it. It is operating at 95-100 psi on 560-850 TDS softened tap water at an average 62 degrees F and still producing 99.4% rejection rate. I pay attendtion to my sediment and carbon block filters, use only the best 0.2 micron absolute rated sediment and 0.5 micron carbon block and change them when I see a drop in pressure. I make a minimum of 11 gallons of water at a time as that is the level the float switches in my ATO storage are set at.

Save any money you would spend on a flush kit and buy better quality sediment and carbon filters and you are money ahead. The tools needed to troubleshoot a RO/DI are an inline pressure gauge, an ATC compensated handheld TDS meter and an inexpensive low range chlorine test kit, these three will help you know where your system is at.