watertight

a. 不漏水的(无懈可击的)

A watertight cylindrical vessel, open at the top and fitted with a handle; a bucket.

桶一种不漏水的圆柱形容器，顶部敞开并安有把手；水桶

Is this roof completely watertight?

这屋顶一点也不漏吗？