It is but natural that, suspicion having once fallen on water as a source or vehicle of disease, means would be adopted not only to properly sterilize water before delivering it to the public, but, furthermore, to select the source of supply where there was least danger of contamination from filth. By this time public water supplies had progressed to such a stage that but few towns, cities or villages of any importance were without a municipal plant. Further, most cities of any importance had a more or less complete system of sewers, and the filth from these sewers was discharging freely, and in the crude state, into the streams and rivers of the realm. Such a condition of affairs could not last long without causing a nuisance, as well as becoming a menace to the health of the commonwealth, and it was not long before the problem was discussed of purifying the sewage before discharging it into streams and rivers. In Great Britain, the pollution of streams was felt more keenly than in America. The population along the rivers in Great Britain is quite dense, and the rivers, which are comparatively small, are used as sources of supply for the different municipalities along the banks, so that some means had to be devised to prevent the people up stream from polluting and perhaps infecting it for those lower down. So early as 1840, this matter forced itself on the attention of Parliament, and in 1843, a royal commission, the Health of Towns Commission, was appointed to inquire into the present state of large towns and populous districts. This was followed in 1857 by the Sewage of Towns Commission, a royal commission appointed to inquire into the best means of distributing the sewage of towns, and in 1865 by the Rivers Pollution Commission, a royal commission appointed to inquire into the best means of preventing the pollution of rivers.