In my mini bogs I drill three hoes, at low, medium and high (say 2” from the top) levels about 3 mm or so and plugged with pieces of wooden skewers, so you can adjust your water levels to suit the weather you are expecting. The low level hole only ever gets openend for winter storage.
Occasional innundations do no har m so long as the water doesn’t remain for say a week or more as the water level prohibits the oxygen from getting into the soil, roots need oxygen and draining also prevents anaerobic conditions.
Cheers
Steve