I leave closed and drain often. I take no chance for having cockroaches finding a nifty place to live and yes...they can easily pass through water in a p trap. Just me... john
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2012 F350 6.7 L dually, 2013 3800RE with 6 pt leveling, Sumitomo 17.5" load range h tires, Samsung 18 cu ft residential fridge, 8k Morryde I.S. with disc brakes. Full timing since 2012.
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