Modave Castle sits on a rocky outcrop high above the Hoyoux river valley, not far from Huy. It is a handsome 17th century castle with Brussels tapestries, Flemish paintings and ornate stucco ceilings.
But you might be surprised to learn that the castle has been owned by the Brussels water authority (now Vivaqua) since 1941. The authority bought the castle to secure an important supply of water that had served the capital since 1922.
The rocks below the castle conceal a vast network of underground channels that capture Ardennes water. It reaches Brussels through a 100km system of underground pipes without any need of pumps.
The water originates from the Hautes Fagnes region where it is slowly filtered through limestone rocks. The same upland area supplies the Spa bottling plant, which means Brussels tap water is almost as pure as expensive bottled water.
Derek Blyth’s hidden secret of the day: Derek Blyth is the author of the bestselling “The 500 Hidden Secrets of Belgium”. He picks out one of his favourite hidden secrets for The Brussels Times every day.