Two weeks after a drain in Hyderabad's Kukatpally burst into froth that was several metres high, officials of the Pollution Control Board (PCB) claimed that it was not a cause of concern.
"Detergents and phosphates were the main reason for the froth. However, it was not chemical froth," N Raveendhar, a senior scientist with the PCB told TNM.
While 1 or 2 mg is considered to be the limit for phosphates in water, Raveendher said that the results showed that the levels were closer to 6 or 7 mg
"It is because of the influence of septic tanks in the area. The pre-monsoon showers were heavy, which caused the incident. We conducted tests to see if it was chemical froth, but that was not the case. Other parameters are well within the limit," he added.
The incident happened on June 8, near Dharani Nagar, which lies close to the Kukatpally nala.
The Kukatpally nala is one of the four major nalas that dump industrial effluents into the Hussain Sagar Lake, and eventually the Musi River. The other ones are the Balkapur nala, Banjara nala and the Picket nala.
Many had also pointed out that this was the same area from where toxic foam overflowed onto the road in September last year.
"Froth is common. It's nothing to worry about. It has happened at the Musi River also two or three times. Whenever surfactant levels are very high and there is free fall of water, this is a common condition," Raveendher claims.
When asked about a possible solution, Raveendher says, "We can't ask people to stop using detergents. Some treatment of sewage is needed. If it was a chemical incident, we would have taken further action, but since it has been proved otherwise, there is no need to do so."
"It is episodal pollution. All the detergents may have accumulated in the septic tank of the house and because of severe rain, all this stagnated water may have been pushed out at once, causing the froth," he concluded.
Watch the video of the earlier incident below.
In January this year, a Telangana RTC bus was engulfed by foam overflowing from the Musi river, in the state's Yadadri District.