Wastewater does not contain harmful chemicals.
At many places the wastewater containing human excreta from homes and carried in big underground pipes is dumped into a river as such which pollutes the riverwater.
(a) What is the common name of such wastewater?
(b) Name five types of harmful organisms contained in it.
(c) Name any five human diseases caused by drinking river water contaminated with such wastewater.
Why does a falling star not cause any harm?