Manual for Recharging Air into RO Pressure Tank

Manual for Recharging Air into RO Pressure TankWhen you turn on the faucet you notice low water pressure from the storage tank and only a quick burst of water come out of the system, and it dies down to trickles. Is the tank defective, i.e., bladder has hole and not functioning properly? Perhaps.

If you have the above problem and the tank is heavy (full), then try to relief the pressure from the air valve on the tank side. Is water coming out? If the answer is yes, then the bladder has hole and is defective, and tank replacement is due. If air comes out then it is possible that the air needs to be recharged.

Notes on bladder tank, please continue reading:

RO Tank useful life is 5-7 years. If the tank has been serving you for that long it is possible that the bladder had a hole and that tank replacement is due. If the tank is not that old, it is worth it to evaluate it for air pressure. In an empty tank, air pressure should be 7-10 psi. In a full/heavy tank, air pressure should be 30-40 psi. To be accurate, air pressure should be 2/3 of incoming water pressure. When the tank is full, and if feed water pressure to the RO system is 60 psi, then a full tank should have 40 psi. The RO tank has a bladder inside, and this bladder separates air from water. On the lower side of the tank is the air valve which is connected to the compressed air chamber. The top water inlet/outlet port (where the tank valve is mounted) is connected to the pure water chamber. So, when you turn on the faucet, the compressed air would squeeze or compress the bladder to force the water out of the tank.

You do not want to believe the tank is useless and want to do extra testing? If your answer is yes, please continue reading.


1. An air compressor or air pump (like a bicycle tire air pump)

2. An air pressure gauge that is able to read less than 10 psi, and

3. Adjustable wrench.


1. Shut off the water supply to the RO system

2. Turn on the faucet to allow water to run until it stops.

3. Check to see if there is still water in the storage tank by lifting the tank. If the tank feels heavy, that means you need to recharge the tank and continue the following steps. If the tank feels light, that means you don’t need to charge your storage tank at this moment.

4. Locate the air valve on the side of the tank. It looks like the air valve on tires.

5. Use air compressor or air pump to pump air into the tank. Keep the faucet on while pumping air, so that all water inside the tank can be purged out.

6. After all water has been drained from the tank, use an air pressure gauge to check the tank pressure.

7. The tank should have 7 psi of pressure when it’s empty. Add or purge air if necessary.

8. Turn the feed water valve back on, and turn off the faucet to allow refilling of the tank.

9. finished.

What if the tank does not hold pressure and you see the same problem again? Bladder is out and you need to replace the tank.