ZETTER BOREHOLE The Zetter has its very own borehole that plunges 1,500 feet beneath the building. In bottling the water, the Zetter continues a tradition reminiscent of Clerkenwell’s 18th century past, when royalty, aristocracy and the likes used to “take the water” from the many springs and spas of Clerkenwell (named after the Clerk’s Well, some 50 yards from the Zetter). The water that isn’t bottled is used to air condition the building and flush our toilets!