watertight
wa.ter.tight. \.wo.t-*r-'ti-t, .wa:t-\ aj 1: of such tight construction or fit as to be impermeable to water 2: leaving no possibility of misconstruction or evasion - wa.ter.tight.ness n
 Webster's English Dictionary
 Webster's English Dictionarywa.ter.tight. \.wo.t-*r-'ti-t, .wa:t-\ aj 1: of such tight construction or fit as to be impermeable to water 2: leaving no possibility of misconstruction or evasion - wa.ter.tight.ness n