APEC ships every ROES-50 and ROES-PH75 with a complete installation kit: color-coded tubing (blue = feed, yellow = waste, red = tank, black = faucet), compression fittings, drain saddle clamp, faucet, and the storage tank. You need three hand tools: an adjustable wrench, a drill with a 1-3/8" bit (for the faucet hole, if drilling a new hole -- not needed if your sink already has an extra hole), and a utility knife for cutting tubing. No special plumbing skills required.
Before you start -- pressure and space check
- Shut off the cold water supply valve under the sink and confirm you have at least 40 PSI. Attach a $10 gauge to verify -- this takes 2 minutes and prevents post-install frustration.
- Measure the under-sink cabinet. The ROES-50/ROES-PH75 manifold is approximately 16" wide x 12" deep x 18" tall. The 3.2-gallon storage tank is roughly 12" diameter x 15" tall. Both need to fit under the sink simultaneously. Most standard kitchen cabinets accommodate both; tight configurations (especially next to garbage disposal units) may require creative placement of the tank in an adjacent cabinet with a tubing run through the cabinet wall.
Step 1: Tap the cold water supply
APEC includes a 3/8" compression angle stop adapter (a T-fitting) that installs between your existing cold-water shutoff valve and the supply line to the faucet. Shut off the main supply valve, disconnect the existing supply line from the shutoff valve, install the angle stop adapter, reconnect the supply line to one port of the adapter, and connect the APEC blue (feed) tubing to the second port using a 1/4" compression fitting. Hand-tighten plus a quarter-turn with the wrench -- do not over-tighten compression fittings.
Alternatively, if your shutoff valve does not accept the APEC adapter (some older or non-standard valves), use a saddle valve -- a clamp that pierces the supply line without disconnecting it. Saddle valves are slightly less reliable long-term than compression tees but are acceptable for most installs.
Step 2: Install the drain saddle clamp
The drain saddle clamp attaches to the kitchen drain pipe (the horizontal run between the P-trap and the wall) and provides a drain connection for RO waste water without cutting into the drain pipe. Position the saddle above the P-trap -- never below it, as this allows P-trap water to back-siphon into the drain saddle. Drill a 1/4" hole in the drain pipe (APEC's included drill bit works for PVC; use a sharp bit for cast iron), install the saddle, and tighten the clamp bolts evenly. Thread the APEC yellow (waste) tubing through the saddle port using the provided compression fitting.
Step 3: Assemble the filter manifold
APEC's filter manifold arrives pre-assembled with filter housings. Thread the pre-installed filter cartridges into their housings in order (Stage 1 leftmost through Stage 4/5 rightmost, following the color-coded label). Hand-tighten housings only -- the included wrench allows a quarter-turn snug, but RO housings crack if over-torqued. Mount the manifold to the under-sink cabinet wall using the included screws (or use the optional horizontal base mounting if you prefer floor-standing).
Step 4: Connect the storage tank
Thread the 1/4" red tank fitting into the tank port (it is a John Guest push-in fitting -- push the tubing in firmly until you feel a click; pull gently to confirm it is seated). Connect the other end of the red tubing to the "TANK" port on the filter manifold's output section. The tank comes with a bladder pre-pressurized to 6-8 PSI from the factory. Do not adjust this pressure until the system is fully plumbed and you have run an initial flush cycle.
Step 5: Drill and install the dedicated faucet
Most kitchen sinks have an extra pre-drilled hole (often covered with a plug) that accepts the APEC dedicated faucet's 1-3/8" shank. If no extra hole is available, drill one: stainless steel sinks require a 1-3/8" step bit and light oil; porcelain sinks need a diamond hole saw and slow speed with water cooling; granite countertops need a diamond core drill and should be done by a professional or very careful DIYer to avoid cracking.
Thread the faucet shank through the hole, secure the mounting nut from below (hand-tight plus a quarter-turn), and connect the black tubing from the manifold's output port to the faucet's supply connection using the compression fitting.
Step 6: Initial flush and leak check
- Open the cold-water supply valve slowly. Check all compression fitting connections for drips -- give each one an additional eighth-turn if any weep.
- Slowly open the dedicated faucet. Expect water to run for 30-60 seconds before pressure builds in the system and the faucet runs consistently.
- Let the system fill the storage tank and run two full tank cycles to drain (fill tank, open faucet until tank empties, repeat). This flushes carbon fines from the pre-filter stages and any manufacturing residue from the housing walls. The water from the first two cycles may appear slightly gray or black from carbon dust -- this is normal and harmless.
- After two flush cycles, the water should run clear. Test with the included TDS meter: output should read 5-20% of your source water TDS. If it reads higher, re-check all connections and allow the system to run a third flush cycle.
Common installation problems and fixes
- Very slow fill (takes hours to fill tank): Supply pressure below 40 PSI. Add a booster pump.
- Waste water running continuously even when tank is full: The automatic shut-off valve (ASO) in the manifold is not closing. Usually caused by low feed pressure -- the ASO needs adequate back-pressure from the tank to close. Verify tank bladder pressure is 6-8 PSI with a Schrader valve gauge.
- Faucet drips continuously: The faucet ball valve seat is not seating. Close and reopen the faucet sharply. If it persists, contact APEC -- faucet replacement under warranty is standard.
- TDS meter reads same as tap water: Membrane is not making contact (tubing routed backward) or the membrane housing cap is not seated. Check that the red and blue ports on the membrane housing are correctly assigned per the installation diagram.