UNICERT is the leading inspection body in the area of water quality test for Total dissolved solids (TDS and objectives to reduce environmental emission/pollution and enhance environmental performance to the society.

Total dissolved solids (TDS:

Total dissolved solids (TDS) is a measure of the dissolved combined content of all inorganic and organic substances present in a liquid in molecular, ionized or micro-granular (colloidal sol) suspended form. Generally the operational definition is that the solids must be small enough to survive filtration through a filter with two-micrometer (nominal size, or smaller) pores.

Total dissolved solids are normally discussed only for freshwater systems, as salinity includes some of the ions constituting the definition of TDS. The principal application of TDS is in the study of water quality for streams, rivers and lakes, although TDS is not generally considered a primary pollutant (e.g. it is not deemed to be associated with health effects) it is used as an indication of aesthetic characteristics of drinking water and as an aggregate indicator of the presence of a broad array of chemical contaminants.

Primary sources for TDS in receiving waters are agricultural and residential runoff, clay rich mountain waters, leaching of soil contamination and point source water pollution discharge from industrial or sewage treatment plants. The most common chemical constituents are calcium, phosphates, nitrates, sodium, potassium and chloride, which are found in nutrient runoff, general stormwater runoff and runoff from snowy climates where road de-icing salts are applied.

The chemicals may be cations, anions, molecules or agglomerations on the order of one thousand or fewer molecules, so long as a soluble micro-granule is formed. More exotic and harmful elements of TDS are pesticides arising from surface runoff. Certain naturally occurring total dissolved solids arise from the weathering and dissolution of rocks and soils. The United States has established a secondary water quality standard of 500 mg/l to provide for palatability of drinking water.

Total dissolved solids are differentiated from total suspended solids (TSS), in that the latter cannot pass through a sieve of two micrometers and yet are indefinitely suspended in solution. The term “settleable solids” refers to material of any size that will not remain suspended or dissolved in a holding tank not subject to motion, and excludes both TDS and TSS. Settleable solids may include larger particulate matter or insoluble molecules.


Effects Low / High TDS of Water:

TDS stands for Total Dissolved Solids in water and represents the total concentration of dissolved substances in water. TDS may contain potassium, calcium, magnesium and sodium along with sodium bicarbonate, sulphate, chloride and nitrate. The accepted limits of TDS in the world in 70 ppm – 700 ppm. (ppm-parts per million)

TDS such as chlorides, sulphates, magnesium, carbonates affect corrosion or encrustation in water distribution system. High TDS level (>500mg/ L) results in excessive scaling in water pipes, water heaters, water boilers etc.  Such scalings shorten the life time of the appliances. It can also cause various diseases in human beings.

Low TDS in water may also cause many problems in the body.  Nowadays most of the people are fascinated to buy water purifiers which are equipped with   the RO (Reverse Osmosis) technology. This RO technology does not allow useful materials in water to enter the body.  Our body needs some salts like potassium and calcium in the body, but the RO does not allow these substances to pass through. Drinking RO water is as good as drinking distilled water, as its ppm is 7 – 8 ppm. Both high and low TDS is harmful for human body.


Interested Parties including Regulatory Authorities:

  1. Persons affected by TDS
  2. Industries, Laboratories using/ Generating TDS
  3. Personal and commercial uses of TDS compounds
  4. Private / Govt. Projects to control TDS
  5. Handling and transportation of goods containing TDS
  6. Local Environmental Department/ Authorities
  7. Local Government Authorities like Municipalities, City Corporation etc.
  8. Local Law Enforcing Agencies like Police, Magistrate and Regulatory Authorities etc.


Benefit of Monitoring:

By monitoring long-term contamination trends, every country establishes baseline contamination levels, making it possible for early identification of contamination events. Daily events and long term trends are captured and taken step to reduce environmental emission/ pollution and enhance environmental performance of the society.