We were asked by a homeowner if their new whole house reverse osmosis system should be removing odors from their well water. This was a commercial system with no carbon filters, just pre-filters and the RO system (not supplied by us).
Many homeowners use under-sink reverse osmosis systems which have carbon filters as part of the system, and those filters do remove odor. This may be misleading some to think that the RO membrane is removing the odors, but it is the carbon filter that is having the effect on the odor.
Generally if odor exists it should be removed prior to under-sink or whole house RO systems for best results and to avoid problems with fouling of the RO system.
While H2S can pass through the membrane as a gas and removed after the RO membranes, it is best practice to remove it prior to the RO system.
Often the odor is a result of a dissolved gas, and gasses will pass through the RO membrane. If the well water has hydrogen sulfide odors, and it is not treated prior to the RO membrane, it can cause problems with slime and build-up on the RO membranes if hydrogen sulfide oxidizes and/or there are sulfur bacteria present.
RO ‘systems’ can remove odors if part of the system is an oxidation filter, carbon filter, aeration or other component that can remove odor. RO membranes by themselves do not remove odor.
We recommended to this customer that they add a Duke Aeration System to remove the sulfur odors prior to the system and this solved the problem.