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). - Bracton.com
- 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 ..
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.
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.