Until about 1815 it was illegal to discharge human waste except into cesspools; "sewers" originally were for rainwater.
 Then the practice gradually changed and in 1846 it became compulsory to drain houses into sewers.
  Sewers had always discharged into the Thames, and so Limehouse Cut itself became another sewer — in the modern sense — and,  when population and industries crowded around its banks, a "very filthy" one.

William Farr wrote that in 1849 some houses near the Lea had no drinking-water supply, so the poor were forced to dip their pails in the Limehouse Cut.
 Apart from the chemical waste, he said, "the canal is a receptacle for dead dogs, cats, and other small animals, frequently seen floating on the discoloured waters; and on every occasion of opening the locks at Bromley there is a rush of floating scum into the Lea'.
 Amongst those who drank the water, deaths by cholera were observed.

As population increased the Lee itself became polluted with sewage, as did the Thames: the sewage was brought in by the tides and locked in the Cut, where it accumulated.
 In 1866 the Lee Navigation's engineer agreed that in hot dry weather the Cut was "An open continuous cesspit ... As foul as it could be.".
In 1877 it was complained the layer of sediment was several feet thick.
Until about 1815 it was illegal to discharge human waste except into cesspools; "sewers" originally were for rainwater.  Then the practice gradually changed and in 1846 it became compulsory to drain houses into sewers.   Sewers had always discharged into the Thames, and so Limehouse Cut itself became another sewer — in the modern sense — and,  when population and industries crowded around its banks, a "very filthy" one.
William Farr wrote that in 1849 some houses near the Lea had no drinking-water supply, so the poor were forced to dip their pails in the Limehouse Cut.  Apart from the chemical waste, he said, "the canal is a receptacle for dead dogs, cats, and other small animals, frequently seen floating on the discoloured waters; and on every occasion of opening the locks at Bromley there is a rush of floating scum into the Lea'.  Amongst those who drank the water, deaths by cholera were observed.
As population increased the Lee itself became polluted with sewage, as did the Thames: the sewage was brought in by the tides and locked in the Cut, where it accumulated.  In 1866 the Lee Navigation's engineer agreed that in hot dry weather the Cut was "An open continuous cesspit ... As foul as it could be.". In 1877 it was complained the layer of sediment was several feet thick.
Limehouse Cut