The best replacement for water seal is suction.

The best alternatives to water seal are rated as following:
★★★★★  suction
★★★  suction chest tube
★★★  dry suction
★★  wall suction
★★  olympic
★  stain deck

Your alternative for water seal is not listed? Suggest!
Speaking about water seal, one probably shouldn't forget about chest tube.

Other search terms related to water seal and their ratings are:
★★★★★ chest tube
You have in mind a companion for water seal and it is not yet here? Propose!



Google Trends

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water seal
suction
suction chest tube