With the revaluation in techniques around 1840, draining was promoted as a productive agricultural improvement. If excess water were effectively removed, draining was credited not only with the physical ability of making land more easily cultivable, valuable in its own right, but also with the potential to enhance crop yields and to transform farming systems, bestowing considerable economic advantages. As landlord and tenant investment in draining was based on the expectation of increasing agricultural output from land injured by waterlogging, the extent to which these benefits were realized had a significant influence on the spread of the improvement. At the same time, an examination of the changes that occurred in farming practice on the adoption of draining is essential for an assessment of the value of the improvement to nineteenth-century English agriculture.

The effectiveness of draining systems

To be a viable and productive agricultural improvement for both landlord and tenant, draining had not only to be effective but durable, with a life that extended beyond the period of interest payment. Contemporary opinion diverged over the improvement's claims to these qualities. While James Caird, George Darby and George Ridley, all Inclosure Commissioners, attested the general reliability of draining carried out from the 1840s to function beyond twenty-five years, the report of the Select Committee of the House of Lords on the improvement of land in 1873, an expression of landowning concern in capital investment in agriculture, carefully identified both the limited life and the likelihood of failure of draining systems. These differing views reflected respective interests in the improvement, but in general the effectiveness of draining depended on the systems and materials employed and the level of subsequent maintenance.