Water testers are tools used to evaluate the quality of water by measuring various properties. While there are many types of water testers, each designed to assess different aspects of water quality, one common method, particularly for determining the level of dissolved substances, involves measuring the water's electrical conductivity.
How Conductivity Testers (TDS Meters) Function
A widely used type of water tester, often referred to as a TDS meter, assesses the presence of dissolved solids in water. However, these devices don't directly measure the weight or volume of these solids.
- Instead of directly measuring total dissolved solids, a TDS meter measures the conductivity of substances dissolved in tap water.
- This method works because dissolved substances, such as salts and minerals, carry electrical charges (ions) that allow water to conduct electricity. Pure water is a poor conductor.
- To measure this, a TDS meter emits a small, harmless electrical current through a water sample.
- The ease with which this current passes through the water is measured as conductivity.
- The higher the conductivity, the more dissolved solids are likely present. The meter then typically converts this conductivity reading into an estimated Total Dissolved Solids (TDS) value, usually expressed in parts per million (ppm) or milligrams per liter (mg/L).
The Conductivity-TDS Relationship
The principle is straightforward: more conductive particles in the water lead to a higher conductivity reading, which correlates to a higher estimated TDS level.
| Water Conductivity (Example) | Estimated Dissolved Solids (TDS) | Implication |
|---|---|---|
| Low | Low | Fewer dissolved substances likely |
| High | High | More dissolved substances likely |
This method provides a quick and practical way to get an indication of the overall concentration of charged impurities in water.
Other Types of Water Testers
It's important to note that the term "water testers" covers devices that measure many parameters beyond conductivity/TDS. For example:
- pH testers measure acidity or alkalinity using electrodes that sense hydrogen ion activity.
- Chlorine testers often use chemical reagents that change color based on chlorine concentration or electrochemical sensors.
- Hardness testers may use titration or test strips sensitive to calcium and magnesium ions.
However, the specific mechanism of measuring electrical conductivity to estimate dissolved solids, as used by TDS meters, is a fundamental principle for assessing one key aspect of water quality based on the reference provided.
