During the 18th century, a new invention, the flush toilet, or water-closet, became more and more popular; the handy chamber-pot kept in the sideboard was no longer socially acceptable. By one of those curious paradoxes that occasionally embarrass the reformer, however, London at the beginning of the 19th Century was more dangerously polluted than ever due to the increase in the provision of these water-closets. The new WCs were so arranged that they discharged into the old cess-pits, which consequently overflowed into the surface water sewers beneath the streets. As these had been earlier designed to collect rainwater only, and to discharge into the rivers and ditches connected to the Thames, the improved domestic arrangements unaccompanied by improvements in the sewerage system brought London to the verge of disaster, a giant step forward for personal hygiene and two steps backward for public sanitation.
In the case of houses backing onto, or near to, the old London streams - the Fleet, the Wandle, the West Bourne, the Ravensbourne, the New, the Holbourne (whence Holborn) and many others, which had been partly or wholly covered over - the domestic closets discharged directly into the streams. Since those on the south side were mostly tide-locked, draining into the Thames only at low tide, the results are better imagined than described; however, much of London's drinking water was still extracted from the Thames, in many cases downstream from the sewage discharge points.