At the 1998 World Aquatics Championships in Perth, Western Australia, Australia Wouda became world champion in the 200 m individual medley and won two silver medals in the 400 m individual medley and the 4×200 m freestyle relay alongside Van den Hoogenband, Van der Zijden and Zuijdweg. In April 1999 at the 1999 FINA World Swimming Championships (25 m) in Hong Kong, China Wouda won four medals. He became world champion in the 4×200 m freestyle alongside Pieter van den Hoogenband, Johan Kenkhuis and Martijn Zuijdweg. He won silver medals in the 400 m individual medley and the 4×100 m freestyle together with Mark Veens, Johan Kenkhuis and Pieter van den Hoogenband, in the 200 m individual medley he won a bronze medal. In the summer of 1999 Wouda took part in the 1999 European Aquatics Championships in Istanbul, Turkey. He successfully defended his title in the 200 m individual medley and won the relay titles in the 4×100 m freestyle, with Kenkhuis, Veens and van den Hoogenband, and the 4×100 m medley with Klaas-Erik Zwering, Stefan Aartsen and van den Hoogenband. He also won the bronze medal in the 400 m individual medley.