By January 1989, "Watermark" had sold over 20,000 copies in Ireland and 300,000 copies in the United Kingdom. Five years later, the album was certified quadruple platinum by the British Phonographic Industry (BPI) for shipment of 1.2 million copies. In the United States, "Watermark" sold 500,000 copies in its first four months of release. After 7 years, the album was certified quadruple platinum by the Recording Industry Association of America (RIAA) for shipment of four million copies. It sold one million copies in the country between March 1995 and March 1996. In November 2008, "Billboard" reported the album had sold 3,877,571 copies in the United States according to figures tracked by Nielsen SoundScan since 1991. Worldwide, the album has sold an estimated 8 million copies.