installed my under sink filter but the dedicated faucet has really low water pressure, barely a stream.

Diagnosis

The low flow issue in the Aquasana AQ-5200 is typically caused by an air lock within the filter canisters or a restriction in the 1/4" LLDPE tubing. When the system is first installed, the filter media is dry and contains thousands of tiny air pockets. As water enters the canisters, these pockets create resistance—essentially acting as a physical barrier that prevents water from flowing freely to the dedicated faucet. If the air is not purged, the water pressure at the spout will remain a trickle regardless of the incoming line pressure.

Another common cause is "tubing collapse" or kinking. Because the AQ-5200 uses flexible plastic lines, pushing the unit back into the cabinet after installation often pinches the output line against the cabinet wall or the cold water shut-off valve. You can confirm an air lock if the faucet "sputters" or coughs air while running. You can confirm a kink by inspecting the line for a white-ish stress mark or a sharp 90-degree bend where the tubing should be curved.

How to Fix It

To resolve the pressure issue and fully prime the system, follow these precise steps:

1. Shut off the cold water supply valve under the sink to depressurize the system.
2. Inspect the entire length of the 1/4" tubing from the adapter valve to the filter head, and from the filter head to the dedicated faucet. Ensure there are no bends tighter than a 2-inch radius. If a kink is found, cut the tubing at the kink and use a new push-to-connect fitting to bridge the gap.
3. Slowly open the cold water supply valve. Do not blast it open; open it halfway to allow the canisters to fill gradually, which reduces the chance of a massive air hammer.
4. Open the dedicated filter faucet completely. You will likely hear a hissing sound or see "milky" water; this is normal and indicates air and fine carbon particles are escaping.
5. Allow the water to run continuously for 10 to 15 minutes. Do not turn the faucet off and on; a steady stream is required to push the air pockets out of the top of the filter housings.
6. If the flow does not increase, close the supply valve, remove the filter cartridges, check that the O-rings are seated perfectly flat against the head, re-insert the cartridges, and repeat the flushing process.

If That Didn't Work

• Check the faucet aerator. The dedicated faucet included with the AQ-5200 has a small integrated screen at the tip of the spout. Debris from the installation process or old pipe scale can clog this screen instantly. Unscrew the tip of the faucet with a small wrench and check for sediment.
• Verify the supply valve adapter. If you are using a saddle valve or an older shut-off valve, the internal orifice may be partially blocked or the valve may not be fully open. Replace the adapter with a full-flow T-adapter if the pressure is low even before the water enters the filter.
• Inspect the filter cartridge orientation. Ensure the filters are pushed firmly into the housing and locked. If a filter is slightly skewed, it can restrict the internal water path, creating a bottleneck that limits flow to the faucet.
• Test for a blockage in the "Quick Connect" fittings. Remove the tubing from the output port and place it in a bucket. Open the water supply. If water gushes into the bucket but not through the faucet, the blockage is in the line leading to the faucet or the faucet itself.

Heads Up

• Avoid using "plumber's putty" or excessive Teflon tape on the push-to-connect fittings; these rely on a precise mechanical seal and over-taping can actually prevent the tube from seating deeply enough, causing a leak or a restriction.
• Always run the water for a full 10 minutes after every filter change to clear the "carbon fines" (black dust) and air pockets.
• Ensure the filter unit is mounted vertically. Mounting the system sideways or at an angle can trap air in the upper canister, leading to permanent low pressure and "hammering" noises in the pipes.
• Check your home's static water pressure. The AQ-5200 requires a minimum of 30 PSI to operate efficiently; if your home pressure is lower, you may experience a slower stream regardless of installation quality.