What are Total Dissolved Solids (TDS) & How to Reduce Them?

According to Wikipedia, Total dissolved solids (TDS) is a measure of the combined content of all inorganic and organic substances contained in a liquid in molecular, ionised or micro-granular suspended form. The Dissolved solids refer to any minerals, salts, metals, cations or anions dissolved in water. This includes anything present in water other than the pure water (H2O) molecule and suspended solids (Suspended solids are any substances or particles that are neither dissolved nor settled in the water).


TDS in drinking-water originates from natural sources, sewage, urban run-off, industrial wastewater, and chemicals used in the water treatment process, fertilizers and pesticides used on lawns and farms and the nature of the piping or hardware used to convey the water. If your water has a moderate to high total dissolved solids content, it can affect taste. The water will taste bitter, salty, or metallic and may have an unpleasant odour. High TDS water is also less thirst quenching. High TDS interferes with the taste of foods and beverages and makes them less desirable to consume. Some of the individual mineral salts that make up TDS pose a variety of health hazards. The most problematic are Nitrates, Sodium, Sulphates, Barium, Cadmium, Copper, and Fluoride.

How do you reduce or remove the TDS in your water?

1. Reverse Osmosis (R.O.) – is one such technology that removes TDS by forcing the water, under pressure, through a synthetic membrane. The membrane contains microscopic pores which will allow only molecules smaller than 0.0001 microns to pass through. Since the molecules of dissolved metals and salts are large compared to the water molecules, the water will squeeze through the membrane leaving the metals and salts behind. The resultant water also tastes very good.
2. Distillation – total reduction with a flat taste
3. Deionisation (DI ) is usually a final polishing filter following a RO Reverse Osmosis filtration system in order to eliminate TDS

To check your Reverse Osmosis membrane performance, the simple way is to use TDS meters. Measure the incoming water and the RO water. Divide the larger number into the smaller number and subtract that decimal from 1. The resulting decimal is the percent of TDS that the membrane is removing. Anyone who wants to know about the quality of their water should have one of these TDS Meter Testers (Source: BayT)


Why should you measure TDS levels in your water?

When TDS levels exceed 1,000 ppm (parts per million) it is deemed unfit for human consumption. A high level of TDS is an indicator of potential concerns and should be investigated before drinking. We are all affected by toxic chemicals in the air and food that we consume. Water is the only way to flush out these toxins so it is important to make sure your water source is providing pure water. This is especially important for children because they are much more sensitive to contaminants because their defence systems have not fully developed. The purer the water, one can be assured of a good health.

These are the reasons why it is helpful to constantly test for TDS:
  • Taste and health | High TDS level will result in bad taste of water which could be salty, bitter, or metallic. It will also indicate the presence of toxic minerals which is hazardous for health.
  • Hardness | High TDS indicates hard water, which causes scale build up in pipes, inhibiting the performance.
  • Industrial and commercial | High level of TDS could affect the functions of certain applications.
  • A constant level of minerals is necessary for aquatic life. The water in an aquarium should have the same levels of TDS as the fish and reef’s original habitat.
  • Pools should monitor the TDS level to prevent maintenance problem.
  • Test your water to make sure the filter system has a high rejection rate and know when to change your filter (or membrane) cartridges.

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