[Explainer]Why TDS fails to be a good way to measure water quality in Malta

TDS Meter MaltaTotal Disolved Solids (TDS) is used by Reverse Osmoisis suppliers in Malta as a way of demonstrating the effectivness of water filters, however it really does fail as a good way to measure water quality in Malta. A TDS meter is used as a key water testing method as it is cheap and easy to do. I bought a TDS tester to try out for less than €20 in Malta and it was really easy to use, just place the probe end in water and bingo you have a reading.The issue is that TDS is very limited in terms of what it is measuring. Sure, it has it's uses but it is just one measure of one factor in water quality so it is really failing to give you a cmplete picture of water quality in Malta.

What are Total Disolved Solids (TDS) in water?

We can start by knowing what TDS is and what it is measuring. Total Disolved Solids are the inorganic salts and small amounts of organic matter that are disolved in water.

The Total Disolved Solids (TDS) are measured in mg per Litre unit of water (mg/L) which is also known as parts per million, ppm.

The following are included in measuring Total Disolved Solids (TDS) in Malta:

  • calcium
  • magnesium
  • sodium
  • potassium
  • carbonate
  • bicarbonate
  • chloride
  • nitrate 

What is a good measure of TDS in tap water?

Typically mineral water and tap water has a TDS measure of 100-200 mg/L which is quite normal.

Areas with higher quantities of minerals in water will have higher readings.

Reverse Osmoisis, ion exchange and distillation water filtration systems will reduce this measure to zero or close to zero. Activated carbon filters will not filter out TDS.

Bottled mineral water will measure higher than tap water, for example Evian comes in at 300 mg/L and San Pelligrino at 850mg/L; we would aspre to drink such healthy mineral waters and trust them to be doing us good, regardless of their TDS measure.

The medical importance of mineral waters depends on the contained amount of minerals and trace elements. Calcium and magnesium in mineral waters are of greatest interest with respect to their potential relevance for the health status; iodine, fluorine and lithium are the most important trace elements. The bioavailability of minerals from mineral water is good and can be compared with the values derived from milk. A positive effect of the minerals in mineral water on health status is especially apparent in the case of insufficient intake by nutrition. The apprehension that there might be an undesired hypertensinogenic effect due to the sodium content in mineral waters is not justified. Sodium is present in mineral water in small amounts only, and mainly as sodium bicarbonate, which has no effect on blood pressure. A certain advantage of a delivery of minerals and trace elements by regular drinking of mineral waters is the simultaneous intake of water, without supply of energy. [Health-related effects of natural mineral waters]

Is a high Total Disolved Solids (TDS) measure a bad thing?

A study by the World Health Organization concluded with the following measures in their Guidleines for drinking water:

  • 50 mg/L to 300mg/L - Excellent
  • 300 mg/L to 600 mg/L - Good
  • 600 mg/L to 900 mg/L - Fair
  • 900 mg/L to 1200 mg/L - Poor
  • 1200 mg/L and above - Unacceptable

Higher TDS waters are described by testers as having a heavier feel to them with very low TDS waters being described as flat.

Why do people use TDS as a measure of water quality in Malta?

The simple answer is that its cheap and easy to do. Just purchase a €20 tester, drop it in a sample before and after filtration and you ahve an immediate "answer".

This measure is particularly used by Reverse Osmoisis companies to promote the use of this filtration system in Malta; but there are disadvantages too for this type of home water filtration system in Malta which we decsribe in our article All about Reverse Osmoisis (RO) home water filters in Malta.

Real tests of water quality focus on the levels of chlorine, pesticides, heavy metals and pharmaceuticals and these require far more analysis and complex testing equipment.

TAPP Water filters have been tested for TDS in tap water with values up to 1000 and the water taste remains good and the water is safe to drink.


Unless your tap water as a TDS value that is vastly outside of the recommended range you have no need to worry. High TDS in your Malta tap water basically means that there is mineral water coming out of your tap. Once you have filtered it to remove over 80+ common contaminants in Malta tap water with your TAPP 2 Twist you will be really happy.

Image credit: Wikipedia

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