Complete DIY installation from official manual V7.2. Assembly, tubing color codes, 7-step install sequence, filter replacement, full troubleshooting reference, and the two mistakes that cause 90% of installation failures.
The Quick Connect fittings at Points G (tank line) and H (faucet line) ship with end plugs that must be physically removed before installation — the most common cause of zero water output after installation. The compression fittings at Points X (feed water) and Z (faucet) require a small plastic insert sleeve inside the tubing end before the nut is tightened — missing the sleeve is the most common cause of leaks at those two points.
| Models | ROES-50 (50 GPD) and ROES-75 (75 GPD) |
| Operating pressure | 40–85 PSI (40–60 PSI normal; 60–85 PSI optimal) |
| Feed water temperature | 40–100°F (4–37°C) — cold water ONLY |
| Max feed water TDS | 2,000 ppm |
| Storage tank capacity | ~4 gallons total; 2–2.5 gallons usable delivery |
| Tank fill time | 2–3 hours from empty |
| Tank placement | Up to 20 feet from RO system; can lie on its side |
| System dimensions | ~17″ L × 6″ W × 18″ H + 11″ D × 18″ H (tank) |
| Source water compatibility | Municipal and private well water |
| Annual filter cost | ~$50–$100/year (depending on water quality and membrane timing) |
| Customer support | apecwater.com/contact • Keep both filter wrenches near the unit |
| Stage | Filter | Part # | Removes | Replace |
|---|---|---|---|---|
| 1 (Right) | Sediment (10-micron) | FI-ES-SED10 | Sand, silt, rust, dirt, suspended particles — first line of defense | 6–12 months (3–6 mo for well water) |
| 2 (Middle) | Carbon Block (10-micron) | FI-ES-CAB10 | Chlorine, chloramines, VOCs, taste/odor, organic compounds — protects membrane | 6–12 months |
| 3 (Left) | Carbon Block (10-micron) | FI-ES-CAB10 | Additional chlorine removal — identical to Stage 2; belt-and-suspenders membrane protection | 6–12 months |
| 4 (Pre-installed) | RO Membrane (TFC) | MEM-ES-50 / MEM-ES-75 | 95–99% of dissolved solids, heavy metals, nitrates, fluoride, arsenic, bacteria, viruses, cysts | City water: 2–4 yrs • Well water: 2 yrs |
| 5 (Inline) | GAC Post-Carbon | FI-ES-TCR-QC | Final taste and odor polish of stored tank water before dispensing | 2–4 years (replace with membrane) |
Memorize these before connecting anything. The critical distinction: compression fittings (Points X and Z) require the insert sleeve; Quick Connect fittings (all others) do not.
Complete this on the floor or a table before going under the sink. Lay the RO system face-up for better wrench leverage.
Remove all wrapping from the three filters and three housings. Stand the housings upright and confirm each has a rubber O-ring seated in its groove. Missing O-ring = guaranteed leak. Do not proceed without verifying all three O-rings are present and properly seated.
Stage 1 housing (RIGHT): insert the sediment filter (FI-ES-SED10). Stage 2 housing (MIDDLE): insert a carbon block filter (FI-ES-CAB10). Stage 3 housing (LEFT): insert the second carbon block filter (FI-ES-CAB10). Stages 2 and 3 use the identical filter and are interchangeable.
Thread order: Stage 3 (left) first, then Stage 2 (middle), then Stage 1 (right). Turn counterclockwise onto the head (reverse of the usual “righty-tighty” direction). Hand-tighten all three before using the wrench. Then wrench-snug each one — firm, not forced. Over-tightening cracks the housing.
Turn off the cold water supply valve (clockwise). Configure the Feed Water Adapter for your pipe size: 1/2″ pipe — attach Converter B to the Male end of Adapter A; 3/8″ pipe — attach Converter B to the Female end of Adapter A. Insert the adapter inline between the cold water supply riser and the shutoff valve. Connect the RED tubing to the adapter compression fitting — install the insert sleeve inside the tubing end before tightening the nut.
Mount above the P-trap on the vertical or horizontal tailpiece — as low as possible to minimize drain noise. Drill a 1/4″ hole through one side of the pipe only. Apply the self-adhesive sponge gasket around the drilled hole. Position the drain saddle clip with the tubing port facing you — align all three holes (saddle, sponge, pipe) precisely before clamping. A misaligned hole blocks drain water and damages the membrane. Push the pre-attached BLACK drain tubing into the Quick Connect on the saddle — no insert sleeve at this connection.
Standard faucet: 1/2″ hole. Air-gap faucet: 1″ hole. Check for an existing unused hole first. For stainless steel: center punch + 1/8″ pilot hole first; clean metal chips immediately. For porcelain: firm downward pressure before starting drill; 1/8″ pilot hole. Thread faucet stem through from above; apply black locating washer (flat side UP for stainless), then lock washer, then lock nut from below — tighten firmly.
Place the main RO system in the cabinet — no wall mounting required. Apply 6–8 wraps Teflon tape to the tank stem threads; screw on the ball valve hand-tight plus a quarter turn with a wrench. Position the tank up to 20 feet away if needed; it can lie on its side. Do NOT touch the Schrader air valve on the tank — it is factory pre-set to 6–8 PSI.
Before connecting any tubing: locate the end plugs in the Quick Connect fittings at Points G and H on the system head. To remove: push in and hold down the collet ring (the square ring around the fitting), then pull the end plug straight out with your other hand. Two types may be present (soft rubber or hard plastic) — remove the same way. Discard the end plugs. Leaving them in is the single most common reason a newly installed APEC produces no water.
Connect in this order to avoid access problems:
Note the “Flow →” arrow on the Stage 5 filter — connect tubing to the correct end. For all Quick Connect fittings: push ALL THE WAY IN until it stops, then pull back gently to confirm locked.
| Filter | Interval | Part # | Notes |
|---|---|---|---|
| Stage 1 Sediment | 6–12 months (3–6 mo well water) | FI-ES-SED10 | Available in FILTER-SET-ES kit |
| Stage 2 Carbon Block | 6–12 months | FI-ES-CAB10 | Identical to Stage 3; replace both together |
| Stage 3 Carbon Block | 6–12 months | FI-ES-CAB10 | If neglected, membrane life drops from years to months |
| Filter housing O-rings | Annually or at each pre-filter change | APEC O-ring kit | Inspect at every change; replace if cracked or hardened |
| Stage 4 RO Membrane | City water: 2–4 years • Well water: 2 years | MEM-ES-50 / MEM-ES-75 | Longevity depends directly on pre-filter maintenance |
| Stage 5 GAC Post-filter | 2–4 years (with membrane) | FI-ES-TCR-QC | Replace at the same time as Stage 4 |
| Stage 1–3 housings (plastic bodies) | Every 5 years | Housing kit | Plastic degrades over time; prevents hairline cracks and slow leaks |
| Symptom | Most likely cause | Solution |
|---|---|---|
| No water at faucet after installation | End plugs not removed at Points G/H; tank ball valve closed; feed supply valve closed; tubing not fully seated | Remove end plugs (push collet, pull plug). Open tank ball valve (handle parallel). Open cold supply. Disconnect and reconnect all QC tubing pushing ALL THE WAY in. |
| Cloudy or milky water | Air from installation + carbon fines from new post-filter — normal | Discard first tank completely. Clears within 1–2 weeks of normal use. Water is safe to drink after flushing even if slightly cloudy. |
| Slow water output | Feed pressure below 40 PSI; clogged pre-filters; fouled membrane; removed/missing flow restrictor; low tank pressure | Check feed pressure (need 40–85 PSI). Replace Stages 1–3 if overdue. Replace membrane if TDS rejection is low. Never remove the black flow restrictor inside the drain tubing. Check tank air pressure (should be 6–8 PSI empty). |
| Filter housing leaking | Missing or damaged O-ring; housing not fully tightened; cross-threaded | Turn off water, relieve pressure, remove housing. Check O-ring condition and seating — replace if damaged. Re-tighten with wrench. If cross-threaded: unthread completely, restart by hand. |
| Leak at compression fitting (Points X or Z) | Insert sleeve not installed inside tubing end; nut not fully tightened | Unscrew nut; confirm plastic insert is fully inside tubing end; reassemble and tighten firmly. If still leaking: apply 8–10 wraps Teflon tape to the threaded stud before reassembling. |
| TDS reads higher than expected | New membrane not fully flushed; membrane fouled or end of life; O-ring bypass on membrane | Flush system several hours and retest. If still high with current pre-filters: replace Stage 4 membrane. Inspect membrane O-ring — replace if damaged. |
| Leak at tank ball valve | Insufficient Teflon tape on tank stem | Turn off water; drain pressure via faucet; remove ball valve; apply 6–8 fresh wraps Teflon tape to tank stem; reassemble and tighten. |
| System doesn’t shut off when tank is full | ASO valve failure; tank air pressure too low to trigger shut-off | Confirm tank ball valve is OPEN. Check tank air pressure when empty (should be 6–8 PSI); add air via Schrader valve if below 6 PSI. If ASO has mechanically failed: contact APEC. |
| Water still tastes like tap water | First tank not flushed; Stage 5 post-filter not primed | Drain the tank completely 2–3 times. Water quality improves significantly after 24–48 hours of continuous operation. |
| Humming noise during operation | Normal sound from flow restrictor in drain line | Normal for most RO systems. To reduce: mount drain saddle on the horizontal tailpiece rather than the vertical, or as low as possible above the P-trap. |
| Connection point | Fitting type | Rule |
|---|---|---|
| Feed water & faucet (Points X, Z) | Metal compression nut | Install plastic insert inside tubing + sleeve over tubing + tighten nut with wrench. If still leaks: add 8–10 wraps Teflon tape to threaded stud. |
| All Quick Connect fittings (A, G, H, W, Y) | Quick Connect (collet-lock) | No inserts, no sleeves, no Teflon tape. Push tubing ALL THE WAY IN; pull back gently to confirm locked. |
| Drain saddle to drain pipe | Mechanical clamp + sponge | Align all three holes (saddle, sponge, drain pipe) PRECISELY before clamping. Tighten screws evenly. |
| Tank ball valve to tank stem | NPT threads | Apply 6–8 wraps Teflon tape to tank stem. Hand-tighten + quarter turn. Do not over-tighten. |
| Filter housings to system head | Threaded plastic | O-ring must be seated in groove. Hand-tighten first; wrench-snug. DO NOT over-tighten. |