Definition of black water in English:

black water

noun

technical
  • [mass noun] Waste water and sewage from toilets.

    Compare with grey water
    • ‘Another plan used grey and black water output to construct a wetland.’
    • ‘You can use water - not your drinking water, but gray water, or water that has been used before but is not yet dirtied to the point of black water.’
    • ‘After consumption, about 80 per cent of the water comes out as waste and this includes black water and grey water.’
    • ‘The sludge disaster was the nation's worst-ever black water spill.’