Membranes have a life expectancy between 2 and 5 years, depending on the incoming water conditions and the amount the RO system is used. This reverse osmosis membrane is critical for effective reduction of total dissolved solids (TDS). The product water should be tested periodically to verify that the system is performing satisfactorily.

Normally, a membrane would be replaced during a semiannual or annual filter change. However, if at any time you notice a reduction in water production or an unpleasant taste in the reverse osmosis water, it could be time to replace the membrane. Desert Mountain Water recommends replacing the membrane when TDS reduction falls below 75%.

You can our TDS calculator to determine the membrane performance.

Note: A water sample may be sent to Desert Mountain Water for a free diagnosis of your membrane performance. To send a water sample, use two (2) clean containers and fill ½ cup of tap water in one container and ½ cup of reverse osmosis water in 2nd container. Clearly label each sample.

Send the samples to

Desert Mountain Water LLC
3301 E Corona Ave.
Phoenix, AZ 85040

Attention “Water Samples”.

Desert Mountain Water LLC will test the TDS within the water and mail or call you with the results. 

Please Note: The membrane service is a part of our Annual Service, If you live in the phoenix metro area we would be able to service your water filtration system ad provide you with the results during or service. Please give us a call to setup an apportionment; Office;  602-774-0981 

Step 1: Turn off the incoming water supply to the RO.

Step 2: Open the RO Faucet and allow water to drain from the tank until it is completely empty.

Step 3: Use a 5/8” wrench to remove the White (Green( Tube fitting on the left side of the horizontal membrane housing (end with one elbow)

Step 4: Remove the cap from the membrane housing by turning it counter clockwise to loosen.

Step 5: Remove membrane housing from the holding clips. Using a pair ofpliers, grip the PVC tube of the RO membrane and pull firmly on the membrane to remove from the housing and discard.

Installing the Membrane

Step 6: Lubricate the O-rings on the new membrane with a water soluble lubricant such as KY Jelly ®. Insert the end with the two black O-rings first into the housing.

Step 7: Once membrane has been inserted into the housing you must take your thumbs and give a firm push to properly seat the membrane. Replace membrane housing cap and tighten.

Step 8: After replacing membrane housing into clips, attach the green tube to the elbow on cap using 5/8” wrench.

Step 9: Follow the Start Up Instructions