Reverse Osmosis Parts & Accessories

OD refers to the tubing's outside diameter. NPT and NPTF identify pipe-thread connections. A fitting marked 3/8 inch OD x 1/4 inch NPT joins 3/8 inch tubing to a matching 1/4 inch female NPT port. Use the connection labels for each end when selecting your part.

Choose the kit that matches your RO system's outlet tubing: 1/4 inch or 3/8 inch. Filter United offers both sizes for routing RO-treated water to a compatible refrigerator dispenser or ice maker. Follow the refrigerator's supply-pressure requirements and the kit instructions.

Start with the space under your sink and the connections on your existing setup. The gallon label describes the tank's nominal size; usable stored water depends on the system's operating pressure and tank air charge. Review the dimensions and connection details on the tank's product page.

They serve different jobs. An RO auto shutoff (ASO) valve controls feed water in a compatible tank-based system as tank pressure rises. The mechanical leak-detector valve uses a water-contact pad to activate its shutoff. Replacement trigger pads are available separately for the matching detector.

The seven-piece O-ring set contains six large seals for compatible prefilter housings and one smaller membrane-housing seal. The wrench set includes tools for filter and membrane housings. Match the seal dimensions and wrench profile to the housings being serviced.

A quick-connect fitting grips a clean, square-cut tube pushed fully into its port. Use the fitting's installation instructions for insertion depth, tubing material, and any retaining clips. Shut off and depressurize the supply before servicing, then restore water and inspect the connection.