Sunday, March 18, 2018

TDS and drinking water quality in Bangalore ..

Total Dissolved Solids (TDS) in drinking water is very crucial to keeping good health and healthy bones. We get our drinking water from many sources.
Total Dissolved Solids (TDS) are the total amount of mobile charged ions, including metals minerals or salts dissolved water, generally expressed in units of mg per unit volume of water (mg/L), also referred to as parts per million (ppm). -

Parts per million (ppm) and milligrams per litre (mg/l) mean the same as the density of potable water at NTP is 1000 kg/cu.m or 1 kg/litre...

As per WHO standards, our drinking water should have the following levels of TDS -
  • upto 300 mgpl or ppm is excellent.  
  • between 300 and 600 ppm is good. 
  • between 600 and 900 ppm is fair. 
  • between 900 - 1200 ppm is poor 
  • above 1200 ppm is unacceptable and dangerous to health.

Click here for a WHO document on the permissible levels of Total Dissolved Solids (TDS) in drinking water ..

In Bangalore we are dependent on Cauvery river for drinking water which has its origin in Talakkavery in Kodagu district at 1270 m above MSL. The Cauvery water is yet to reach major parts of Bangalore with the result that people have drilled borewells for water, both for drinking and washing and other purposes.

A TDS meter is a small electric contraption which I bought off Amazon, as an Amazon choice for less than Rs 500/-. It works on the electrical conductivity principle. Higher the TDS, more the dissolved solids, ions and conductivity and hence higher the current that passes. For industrial purposes, we need water with practically zero or near zero TDS. But for drinking purposes, we have water with varying degrees of TDS depending on the source from which we get it.

In the industry, when I was in the Utilities department in the MRF factory in Goa, we used to get upset when the TDS in the distilled and specially treated water used in the industrial process for generating steam, hot water etc used to go beyond even 10 ppm. More dissolved solids in the water in the form of ions, greater inefficiency of heat transfer as the pipes used to be clogged with scales.. 

I did a causal TDS checking of water in my house at 12 noon on 17 March 2018. I have water from three sources being used at home. One is from the river Cauvery (A), this Cauvery water is collected in  TATA Swach water filter which helps remove suspended solids (measured by Total Suspended solids) and is boiled for drinking water purposes (B) and the third source is the borewell water (C) used for washing, watering, bathing and cleaning purposes.

After collecting a couple of samples, took the measurement at least five to six times, and after some statistical analysis of data (through an interesting Android smartphone statistics app called SIGMA), got the following average values of TDS.

A - 213 mg/l  - Cauvery water was found to have TDS of 213 mg/l (ppm)
B - 210 mg/l  - Cauvery water after being filtered through a TATA SWATCH filter and
C - 405 mg/l  - Borewell water collected from a depth of about 300 ft.

At depths of 950 ft and 1500 ft in Electronic city area, the borewell water is found to have TDS of about 660 ppm.

Click here for a  Bangalore mirror report of the declining water quality in different parts of Bangalore.

Water is an essential input in our life and one of nature's most desired, available and needed resource after sunlight. Let us use it with great care and caution, so that our future generations too will get to use it at the same level at which we use it now.



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