[jeffba]

With the residential fridge and washer it took 4 gallons. Without the washer it was less than 3.

I blew it out first.

I put the bucket on an 8 foot ladder. There was no gasket and screen so I needed to borrow one from the city hookup. I reversed the screen to push in on the backflow. I did not prime the hose. Pump pulled it just fine.

Only hard part was keeping bent over while cycling the icemaker til the cube tray was pink. Clean up was easier by leaving the cube bucket in.
Cell phone set to selfie made finding the icemaker test button easier. (it is on the bottom of the icemaker)

There is no low point drain or reachable shutoff valve on the LKs for the refrigerator

To do this I used the winterizing port and let the waterpump push the antifreeze through.

Does this help ya?