Reverse Osmosis Membranes

A reverse osmosis (RO) membrane is the part of an RO system that does the purifying. Pressure pushes water through a thin-film composite (TFC) membrane; purified water passes through, and dissolved salts, hardness minerals and many other dissolved contaminants are rinsed away to the drain. The sediment and carbon pre-filters in the system are there to protect the membrane, and the post-filter polishes the water after it.

How to choose a replacement RO membrane

• Under sink membranes are 1.75" x 11.75" and come in 50, 75 and 100 GPD (gallons per day). Match the size to your membrane housing and the GPD rating to your system.
• Whole house, commercial and industrial elements come in 2.5" x 14", 2.5" x 21", 2.5" x 40", 4" x 40" and 8" x 40". The size is set by the pressure vessel, so measure the element you have or the vessel it sits in. Larger systems often run several elements, and they are replaced as a set.
• Match the membrane to your feed water. Freshwater RO membranes are for tap and well water under about 2,000 ppm TDS (total dissolved solids). Brackish water RO membranes are for saltier well and surface water, and seawater desal membranes are for desalinating ocean water. A TDS test of your feed water tells you which class you need.

When to replace an RO membrane

An under sink membrane usually lasts 2 to 4 years when its pre-filters are changed on schedule. Freshwater commercial elements are planned for about 2 to 3 years. Actual life depends on feed water quality, pre-treatment and how much water the system makes. Signs a membrane is due: the TDS of the purified water climbs, output slows even with fresh pre-filters, or the water starts to taste mineral again. Commercial elements can often be cleaned first with membrane cleaners; replace them when cleaning no longer brings output and quality back.

Step by step help: how to replace an RO membrane and how to clean an RO membrane.

Our membranes are industry standard sizes, so they fit standard RO membrane housings and pressure vessels of the same size whatever the brand, including Crystal Quest systems.