The product you want is called an Apex Filtamate model no. FM85PSI or FM50PSI. This is a pressure reducing valve specifically manufactured for your application and goes in the line to your RO machine which will not affect any other pressures in the house. The 85 PSI is usually used for RO machines. If you are in the USA contact Good Waterwarehouse ph. 714 441 2893 or fax 714 441 0525 and they will advise you of a stockist near you.