i get a burst of air or sputtering water every time i first open the apec faucet

Diagnosis

The sputtering or "burping" effect experienced with the APEC ROES-50 is caused by trapped air pockets residing in the delivery line between the pressurized storage tank and the RO faucet. This typically occurs because the system is a closed-loop pressurized environment; when you replace the pre-filters or the membrane, air enters the housing. If the system sits idle for several days, small amounts of dissolved gases can also coalesce into larger bubbles that migrate toward the highest point of the plumbing—usually the faucet or the top of the storage tank.

You can confirm this is an air-lock issue rather than a mechanical failure by observing the flow rate. If the water comes out in a violent, erratic spray for 3-5 seconds and then settles into a steady, strong stream, it is simply trapped air. However, if the sputtering is accompanied by a very weak flow that never recovers, you likely have a depleted bladder in the storage tank or a kink in the 1/4" LLDPE tubing. In most cases with the ROES-50, this is a benign byproduct of the system's design and the physics of air displacement in narrow-bore tubing.

How to Fix It

To properly purge the system and eliminate the air pockets, follow these steps to ensure all gas is evacuated from the line and the tank is properly primed:

1. Close the cold water supply valve leading to the RO system to prevent new water from entering the pre-filters during the initial purge.
2. Open the RO faucet fully. Let the water run until the flow stops completely. This empties the current pressurized volume of the tank.
3. Slowly open the main cold water supply valve. This forces new water through the 5 stages and into the tank, pushing existing air pockets forward.
4. Wait approximately 20 minutes for the tank to begin refilling. You will hear the water rushing into the tank.
5. Open the RO faucet again. You will likely experience the sputtering burst. Do not close the faucet; let it run for a full 60 to 90 seconds. Use a pitcher to catch the water to avoid splashing your countertops.
6. While the water is running, gently shake or wiggle the 1/4" tubing leading from the tank to the faucet. This helps dislodge air bubbles clinging to the inner walls of the tubing.
7. Close the faucet and allow the system to reach full pressure (usually 2-4 hours).
8. Perform one final "flush" by opening the faucet for 10 seconds to clear any remaining micro-bubbles.

If That Didn't Work

If the sputtering persists after a full purge, try these advanced troubleshooting steps:

• Check the Tank Pressure: Use a low-pressure tire gauge to check the air valve (Schrader valve) at the bottom or side of the storage tank. With the tank empty of water, it should read between 7 and 10 PSI. If it is significantly higher or lower, the air-to-water ratio is off, which can cause erratic discharge. Adjust the pressure using a handheld bike pump.
• Inspect for "Air Leaks" on the Suction Side: Check the push-fit connectors on the pre-filters. If a fitting is slightly loose, it may not leak water out, but it can allow air to be sucked into the line via Venturi effect, creating a constant stream of bubbles. Push the tubing firmly into the fitting until it seats against the internal stop.
• Reset the Tank Orientation: If the tank was accidentally tilted during installation, air can trap in the top dome. Ensure the tank is standing perfectly vertical. If possible, slightly loosen the tank valve for 2 seconds to let a "burp" of air escape, then tighten it immediately.
• Replace the Post-Carbon Filter: If you recently installed a new final stage (the horizontal polished carbon filter), it may contain trapped air in the carbon media. Remove the filter, reinstall it, and run the water for 5 minutes to fully saturate the carbon block.

Heads Up

• Avoid Over-Pressurizing: Never pump the storage tank above 12 PSI when empty; doing so can collapse the internal bladder and permanently ruin the tank.
• Filter Change Protocol: Whenever you change the ROES-50 filters, always run the water for 10 minutes before drinking to flush out carbon fines and air.
• Tubing Kinks: Ensure the 1/4" tubing has wide, sweeping curves. Tight bends can create "air traps" where bubbles collect and cause the sputtering you are experiencing.
• Leak Check: After purging air, always run your finger around the push-fit connections to ensure no drips developed due to the increased vibration of the sputtering water.