The swivel transfers the high-pressure water from the hose to the drill string. Wassara Swivels are designed and dimensioned to be robust and withstand the high pressure during water-powered drilling.
A top mounted swivel is placed above the rotation unit (when drilling downwards). This is the primarily choice when the rotation unit can handle the high water pressure.
An in-line swivel is mounted below the rotation unit and the alternative when a top mounted swivel is not preferred.