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Aquasana Install-hub

How to Install the Aquasana OptimH2O Reverse Osmosis System

Aquasana OptimH2O installation guide: cold water tap, drain saddle, manifold, storage tank, Claryum post-filter stage, and dedicated faucet. Standard 60-90 minute DIY install.

Updated Aug 2026 · Aquasana RO Systems

The Aquasana OptimH2O installation follows the same structure as any under-sink RO: cold supply tap, drain saddle, filter manifold, storage tank, dedicated faucet. The specific step worth attention is the Claryum post-filter stage placement -- it must be installed as the final filtration stage before the faucet, not before the tank. This is how the selective mineral retention works: the Claryum medium has the last contact with the water before it dispenses.

Contents of the OptimH2O installation kit

  • 5-stage filter manifold with pre-filter stages installed
  • Integrated RO membrane + Claryum post-filter unit (combined in a single housing -- do not separate)
  • 3.5-gallon storage tank
  • Dedicated brushed nickel faucet
  • Cold water supply T-fitting (3/8" to 1/4")
  • Drain saddle clamp with 1/4" tubing adapter
  • Color-coded tubing set and compression fittings
  • TDS meter

Step 1: Cold water supply connection

Shut off the cold supply shutoff valve under the sink. Disconnect the supply line from the valve's output port. Install the Aquasana T-fitting between the valve and the existing supply line. Connect the blue (feed) tubing from the OptimH2O manifold's inlet port to the second port of the T-fitting. John Guest push-in fittings throughout -- push firmly, confirm with a gentle pull.

Step 2: Drain saddle

Identify the kitchen drain horizontal pipe (between P-trap and wall). Mount the Aquasana drain saddle on the top or upper side of the pipe -- above the P-trap, never below. Drill a 1/4" hole in the pipe (included drill bit). Tighten saddle clamp bolts evenly. Connect the yellow (waste) tubing from the manifold's drain outlet to the saddle port.

Step 3: Filter manifold and Claryum stage

The OptimH2O manifold has filter stages in order from left to right. The integrated RO membrane + Claryum unit installs in the main membrane housing -- this is a single combined module, not two separate cartridges. Do not attempt to separate the membrane from the Claryum housing; the combination is designed as a unit and separating them voids the NSF 401 certification. Insert the combined module with the feed end (marked on the module) entering the housing first. Close the end cap firmly.

The remaining pre-filter stages (sediment, carbon block) install in the left housings. Mount the manifold to the cabinet wall with filter housings oriented downward for servicing access.

Step 4: Storage tank and post-filter routing

Connect the red (tank feed) tubing from the manifold's post-membrane output to the storage tank's 1/4" port. The storage tank is in the RO circuit before the Claryum post-contact stage on some OptimH2O configurations, and after it on others -- check the included diagram carefully. The Aquasana design places the Claryum as the final stage after the tank in most current OptimH2O configurations. Confirm tubing routing against the diagram before closing the cabinet.

Step 5: Dedicated faucet installation

The OptimH2O includes a brushed nickel faucet that installs in an extra sink hole (most standard kitchen sinks have a fourth hole covered by a plug -- remove the plug). If no extra hole is available, drill a 1-3/8" hole in the sink or countertop. Thread the faucet shank through from above, secure the mounting nut from below, and connect the black (output) tubing from the manifold's Claryum post-filter outlet to the faucet's lower port.

Step 6: First flush procedure

Open the cold supply valve slowly. Wait 20-30 minutes for the system to cycle through its initial fill. Open the dedicated faucet and run until flow slows significantly (tank full). Empty the tank completely by opening the faucet. Repeat twice. First-cycle water may appear slightly gray from carbon medium conditioning -- harmless. After two flush cycles, measure output TDS with the included meter. Expected range: 50-120 ppm from 200-400 ppm source (the Claryum stage retains some mineral content, so output TDS will be higher than bare-RO systems -- this is normal and expected).

Pairing with Aquasana Rhino

If installing the OptimH2O as part of an Aquasana Rhino + OptimH2O whole-home stack: the Rhino installs at the main supply line entry point and treats all household water. The OptimH2O installs under the kitchen sink on its own cold supply tap -- it draws from the Rhino-treated feed water. The Rhino's chloramine removal pre-treatment reduces the load on the OptimH2O's pre-filter stages, extending pre-filter life from 6-12 months to 12-18 months in most household configurations. The OptimH2O membrane interval remains 24 months regardless of pre-treatment.