Answer: A high-air entry filter can be saturated as follows: Remove the filter. Saturate it in deaired water. Replace the filter while holding the piezometer underwater. Bag the piezometer in deaired water to maintain saturation until installation.
To prepare deaired water, boil the water and apply a vacuum or use a device such as a Nold DeAerator, which combines propeller cavitation with a vacuum to deair the water rapidly.
To saturate the filter, place stoppers in the top and bottom of the filter. Place a vent tube through the stopper at the top of the filter. Immerse the filter in deaired water. Water flowing through the filter will displace the air inside the filter, which flows out the vent tube. Allow the filter to remain in the deaired water for 24 hours.