Letters patent appointing Commissioners, 1727-1840; writs to swear in Commissioners and to summon juries, 1727-1830; qualification book containing forms of declaration of £100 property owners, 1834-1844; court minutes and presentments, 1569-1642; court minutes, 1677-1781; court orders, 1703-1781; court minutes and orders, 1781-1847; General Purposes Committee minutes, 1820-1847; plans and sections of sluices, sewers, washways, culverts, roads, streets and wharves; original presentments of juries, not reproduced in full in the minutes, 1743-1793; out letter books, 1833-1848; financial records, 1789-1854 and rate books, 1723-1848.

Papers of Professor William Cawthorne Unwin, 1856-1952, comprising correspondence, principally concerning engineering matters, 1856-1931, 1950,1952, notably with Edward Dean Adams, including the Niagra Falls Scheme, 1890-1929, Sir Benjamin Baker, including the Forth Bridge, dam schemes, 1882-1898, Sir William Fairbairn, including experiments, appointments, 1856-1874, Thomas Hardy, concerning astronomy, 1881, Imperial College, 1910-1926 (as representative of the Institution of Civil Engineers);
research papers, 1859-1924, notably Fay and Newall brakes, 1859, observations on the Thames, 1882-1883, Nile Project Committee, 1919, dam schemes, 1899-1905;
speeches and addresses to various institutions, including presidential addresses to the Institution of Civil Engineers, 1912, and Institution of Mechanical Engineers, 1916; engineering drawings, 1875-1906, of apparatus, machinery, sections of the Thames, Telok Ayer key wall, Singapore; two portraits of Unwin, undated;
additional material, comprising papers relating to Windsor Water Works arbitration, 1884; reports on compression gauges, 1886-1887; Birmingham dams, 1895; notes on dam theory, 1905; papers relating to Stockport water supply and Kinder Dam, 1905; notes relating to schemes for Niagra and central London.

Records, 1872, of Rosario and Cordova Water Works Company, comprising prospectus, memorandum of association, and contract for acquisition of concession and construction of works, with plans attached.

Record books, 1902-1905 and 1921-1922, relating to the examination of water and water supplies.

Papers, 1881-1891, of Donald James Mackay, 11th Baron Reay, as Governor of Bombay, comprising correspondence, memoranda, petitions and other papers, 1884-1889 and undated, on A'bkari administration (a system of licences for the distillation and sale of spirits in Bombay); correspondence, memoranda, minutes, reports and other papers, 1881-1891 and undated, relating to military and naval subjects; correspondence, memoranda, minutes and reports, 1885-1890 and undated, on education; correspondence and other papers, 1881-1891 and undated, on agriculture; correspondence and other papers, 1884-1889 and undated, on sanitation and water works; correspondence and papers, 1884-1891 and undated, on various other subjects including administration, hospitals, irrigation, railways and finance; addresses of welcome to Lord Reay, 1886-1890 and undated; a drawing of Bombay harbour and accompanying manuscript plan, undated; manuscript map of Karachi Harbour Board, 1887.