Records of the Lee Conservancy Catchment Board, including minutes of Board meetings; papers relating to staff including wages and superannuation; papers regarding the Sadler's Mill stream diversion; papers regarding flood relief and defences; correspondence and papers of the Association of River Authorities; papers relating to clearing the river; petitions; rainfall statistics; fishing rights; papers regarding members of the Board; drainage schemes; public relations files; papers regarding the Water Resources Act 1973; reports; papers regarding the acquisition of properties; and agreements for works, clearing, drainage, diversions, improvements, flood prevention, land sales and so on.

Records of the Metropolitan Water Board Treasurers and Comptrollers Department, including detailed balance sheets; Water Fund general ledgers; general journals; cash accounts ledgers; superannuation volumes; capital ledgers; borrowing powers volumes; investments volumes; mortgage sinking fund volumes; stock volumes; audit files; files relating to stocks and shares; mortgage loans files; registers of bankruptcies and liquidations and salary records.

Minutes of the New River Company, including minutes, papers and reports of Weekly Meetings, of the General Courts of Governors, of the Surveys of the River Committee, of the Parliamentary Committee, of the Building Committee and of the River Lee Conservancy Board. Also copies of the charters of 1606 and 1737.

Financial records of the New River Company, including abstracts of accounts; balance sheets; ledgers; collectors ledgers; journals; disbursement books; cash books; revenue account books; audit books; bill book; bill cheque books; taxes and rates ledgers and accounts; landed estate accounts and meter rent books.

Records of the South London Waterworks Company (later the Southwark and Vauxhall Water Company) including papers relating to shares; minutes of Director's meetings; stock certificates; papers relating to works and papers relating to a lawsuit.

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 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.

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.