Commissions of sewers, originally known as commissions de wallis et fossatis (Law Latin: "commissions of walls and ditches [or dikes]")[1] were English public bodies, established by royal decree, that investigated matters of land drainage and flood defence. The commissions developed from commissions of oyer and terminer in the 13th century and had powers to compel labourers to work on flood defences and extract funding for repairs from landowners. The commissions were placed on a statutory basis in 1427 by an act of Parliament, the Sewers Act 1427 (6 Hen. 6. c. 5) and were strengthened by later acts such as the 1531 Statute of Sewers and the Commissions of Sewers Act 1708. The commissions were abolished by the Land Drainage Act 1930, though some survived until after the Second World War. Their duties were assumed by internal drainage boards and river authorities.
Records have not survived from commissions before the early modern era but later commissions sat in sessions similar to the judicial quarter sessions. Commissioners, appointed by royal order, were sometimes known as "justices of sewers". Key officers included the clerk, expenditor (treasurer) and bailiffs (elected by each parish). Other local officers were also sometimes appointed to enforce orders of the commission.