The kitchen is a place where fire and water blend. Pay attention to the wind direction and current. It doesn't matter if it's lower, but it shouldn't make people walk with a sense of steps.
Because the access to the kitchen is a waterway in geomantic omen. Should be based on the premise of patency.
It's low. It should be water.
The toilet should be arranged at the water station, which can be lower.
Personal suggestions for your reference.