the storage tank on my apec roes-50 feels empty or only gives a couple cups of water. how do i fix it?

Diagnosis

The ROES-50 utilizes a pressurized bladder tank to store purified water. Inside the steel shell, a rubber diaphragm separates the purified water from a pocket of compressed air. This air pressure is what physically pushes the water out of the tank and up through your faucet. When the tank feels heavy (indicating it is full of water) but only delivers a small amount of water before the flow stops, the tank is "waterlogged." This happens because the air charge in the bladder has leaked out over time or the bladder has lost its elasticity. Without the 7-8 PSI of pre-charge pressure, the water has no motive force to leave the tank. You can confirm this by lifting the tank; if it feels significantly heavier than usual but the faucet only gives a trickle, the air pressure is gone. If you press the Schrader valve (the air intake) and water squirts out instead of air, the internal bladder has ruptured completely.

How to Fix It

To restore the pressure in your APEC ROES-50 storage tank, follow these exact steps to avoid damaging the bladder:

1. Close the cold water supply valve to the RO system and close the tank ball valve (the blue or white handle located on top of the tank).
2. Open the RO faucet on your sink and leave it open. This releases the remaining pressure in the lines.
3. Locate the air valve (Schrader valve) on the bottom or side of the tank, usually protected by a plastic cap.
4. Use a standard low-pressure tire gauge to check the current PSI. If the tank is full of water, the reading will be inaccurate; you must drain the tank first.
5. Slowly open the tank valve and allow the RO faucet to run until the water stops flowing completely. The tank is now empty of water, allowing you to measure the "pre-charge" air pressure accurately.
6. Using a bicycle pump or a portable air compressor, pump air into the valve.
7. Check the gauge frequently. You must reach exactly 7 to 8 PSI. Do not exceed 10 PSI, as over-pressurizing can collapse the bladder or prevent the RO membrane from filling the tank.
8. Once 7-8 PSI is reached, replace the valve cap and reopen the tank ball valve and the main water supply.
9. Allow the system to refill (this may take 2-4 hours) and test the flow at the faucet.

If That Didn't Work

• Ruptured Bladder: If you pump air into the valve and hear a hissing sound, or if water emerges from the air valve, the internal rubber diaphragm has a hole. There is no way to patch a bladder; you must replace the tank. For the ROES-50, ensure you buy a replacement tank with the same gallon capacity (typically 2.0 to 3.2 gallons) to maintain system balance.
• Clogged Tank Valve: If the tank is pressurized and full, but water won't flow, the tank ball valve may be stuck or clogged with sediment. Remove the valve and check for debris, or replace the valve entirely.
• Faultile Auto-Shutoff Valve (ASO): If the tank never fills up in the first place, the ASO valve (the square plastic component on the manifold) may be stuck in the "closed" position, preventing water from ever reaching the tank.
• Membrane Failure: If the system is producing water so slowly that the tank never actually fills, your RO membrane (the main filter) may be fouled. Check the TDS (Total Dissolved Solids) of the water; if it is nearly the same as your tap water, the membrane is spent and must be replaced.

Heads Up

• Pressure Balance: Never inflate the tank while it is full of water. The water pressure will give you a false high reading on your gauge, and you will under-inflate the bladder, leading to the same "waterlogged" problem within weeks.
• Valve Leakage: Check the Schrader valve for slow leaks after inflating. A small dab of silicone grease on the valve pin can help create a better seal.
• Seasonal Changes: Extreme temperature drops in unheated basements can cause air pressure to drop. It is a good practice to check the tank PSI once a year.
• Flow Rate: Remember that the ROES-50 is a slow-filtration system. If you have a leak in your drain line or a faulty check valve, the tank may never reach full pressure even if the air charge is correct.