Madurai: The quality of the ground water, which is used for many
purposes except drinking, in the city and its outskirts is fast
degrading. While the total dissolved solids (TDS) was found to be high
in deeper borewells, it was worse in shallower ones too, probably due to
external contamination, reveals a survey on TDS in ground water, conducted by Rainstock, an organization working on rainwater harvesting, on the occasion of World Water Day.

Founder of Rainstock, K Sakthivel, said they had done the survey in
various parts of the city for the past three weeks, and found that the
TDS had increased many fold in some places when compared to the
statistics obtained during a similar survey in 2015. According to the
World Health Organisation (WHO), any TDS concentration below 1000
mg/litre is acceptable to be used by consumers. The Bureau of India
Standards (BIS) has fixed the upper limit for drinking water at 500 ppm
(parts per million). TDS comprises organic salts and small amounts of
organic matter that are dissolved in water.

The members of the organisation had also engaged students in the
survey and pamphlets and questionnaires were handed over to the
residents, to find the depth of their residential bores and many of them
had said that they had gone for deepening of their old wells, while
many houses had said that they had multiple borewells in their homes to
meet their needs.

Some places like Iravathanallur, Thiruparankundram, Kochadai, Pamban
Nagar, among others had a ground water level, where water was available
at 250 feet. Whereas in places like Gomathypuram, Aathikulam and
Jahindpuram, which were in the vicinity of huge water bodies such as the
Vandiyur tank, water was available beyond a depth of 450 feet. The TDS
in Gomathypuram on an average was 1704 ppm.

Many residents of the city are prone to seeking residences in places
where there is a good ground water table at around 250 to 300 feet,
since it would ensure that they would not have to face a water crisis
during drought periods. “But, the irony is, that in places where there
is copious ground water, the TDS was seen to be hovering along the
danger limit during our survey,” Sakthivel said.

For example, in Iravathanallur where the average ground water level
was 295 feet, the TDS stood at an alarming 1237 ppm. Though the survey
had not gone into the individual elements in this water, Sakthivel says
that many minerals could be harmful if they exceed the limit and that
the high TDS is a result of contamination from external sources
including open sewage.

Another example was Pamban Nagar, which is situated near the
corporation dumping yard in Vellakkal, where the ground water was
available at a depth of 170 feet, but the TDS was 2,960 way above the
permissible level of 1000 ppm. Residents had told the survey team that
there water had been good before the dumping yard was established.
Though water is available at a very accessible depth these people get
their drinking water from a place eight km away.

TDS levels in areas in – 2015 – 2017

K K Nagar – 405ppm – 1208 ppm

Thiruparankundram – 717ppm – 936 ppm