A water board is a public body established on the basis of the Water Board Act that has the task of regulating water management in a specific region in the Netherlands. The term water board is also used to indicate the region over which that body has control. The area is partly determined by municipal or provincial boundaries, but mainly by river basins or drainage areas in a specific region. Six water boards in Utrecht, South and North Holland bear the name water board instead of water board. As of May 17, 2018, there are 21 water boards in the Netherlands, in 1950 there were approximately 2,600.

Water boards are one of the oldest institutions in the Dutch constitution. Sources are scarce, so that it cannot be said with certainty about the early history of water boards. With the Great Mining (10th century), the Dutch landscape was brought into culture. Due to the settling of the soil, it became necessary to create polders and drainage. For the count’s time, this was the responsibility of the neighboring assembly. Only the neighbors, the owners of a full farm, had a voice and access to board positions. Their task was to take care of new and existing dikes and waterways. The division in it took place according to the track. People were chosen from the local communities to check maintenance, the so-called inspection. Disputes were submitted to local councilors, originally elected from the local population. Under the influence of changes in count law and administration, local polder administrations started to cooperate from the 13th century, which eventually led to the water boards. The first official water board was the Rijnland Water Board, which was established in 1255 by Count Willem II of Holland. The Schieland Water Board dates from 1273 and that of Delfland from 1289. Count Floris decided in the 13th century that his delegate in Rijnland would be called dijkgraaf . That title was later widely adopted.

Regional water authoritiesform the basis of the polder model: traditionally, water boards have had the task of regulating water management on behalf of the residents of a specific area. In polders this is primarily the concern for the water level. It is true that pumping stations have taken over the task of the windmill almost everywhere, but the land still does not remain dry by itself. Keeping out water and draining excess water has traditionally been a general interest, whereby polder residents were forced to work together. The water boards have arisen from this necessary cooperation. They also occupy a special place in Dutch legal history. In the constitution of 1848, the task of water management is assigned to the water boards.

Prior to 2005, there were umbrella water boards, such as Rijnland, responsible for the water basins, with smaller “inland” water boards. There was also overlap due to the existence of water boards specifically charged with the seawater defense and purification boards. As a result of mergers, the internal water boards and specialized boards have been phased out, so that since 1 January 2005 all water boards are responsible for both the quantity (water level) and the quality of the water. There are also no more overlapping areas, each part of the (European) territory of the Netherlands now falls under one water board.