WiseLite TDS (Total Dissolved Solids) Indicator


SKU: 1505 Category:


The WiseLite TDS Indicator is a water tester that demonstrates the presence of Total Dissolved Solids (heavy metals, inorganic minerals, salts) in water. This Total Dissolved Solids tester consists of a 5-watt bulb in a socket attached to two separate bare copper wires connected to an electrical cord and encased in a protective plastic tube.


Most people are surprised to learn pure distilled water is essentially a nonconductor of electrical current. When the WiseLite TDS Indicator is plugged into a 120-volt outlet and partially immersed (bulb up) into a glass of high-quality distilled water the bulb will not light. If a pinch of common table salt (sodium chloride) is added to the distilled water, the sodium (Na+) and the chloride (Cl-) ions traveling back and forth between the wires cause the circuit to be completed and thus the bulb will glow. The higher the concentration of salt, the brighter this Total Dissolved Solids tester will glow.


Repeating the same procedure with a new glass of distilled water and sugar (an organic compound) will not cause the light to glow since most organic substances are non-electrolytes. Most tap waters have electrolytes present in the form of inorganic Total Dissolved Solids; the higher the concentration of electrolytes, the brighter the WiseLite TDS water tester will glow.



  • For use with 120 Volt AC electricity only
  • One clear and one red 5W light bulb included
  • Length: 6″ nominal
  • Diameter: 1″ OD
  • Cord length: 68” nominal

Purpose: To show the presence of dissolved solids in tap water.


  • One (1) WiseLite
  • One (1) glass of pure distilled water
  • One (1) glass of ordinary tap water
  1. Fill one glass with distilled water. Fill the other glass with tap water.
  1. Plug the WiseLite into a 120 volt AC outlet.
  1. Check the purity of the distilled by immersing the open end of the WiseLite approximately 2-3 inches into the water with the bulb up. Do not submerge above the  blue indicator line. The light should not glow.
  1. IMPORTANT! Remove WiseLite from glass.  Now, dip your fingers into that glass and rub them together. DO NOT place fingers in water with WiseLite!
  1. Now that you have “washed” your fingers in the distilled water, check again with WiseLite. It should glow faintly as the water is now impure. The glass of water you washed your fingers in is not all that dirty. It was pure water to start with and your hands are basically clean. However, you never know what may be in your tap water.
  1. Next, check the tap water with the WiseLite. The light will glow brightly in most tap waters.  The brighter the light, the more dissolved solids in the water!


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