Electrolysis is a chemistry experiment that is sometimes used to test water samples and “prove” how contaminated a given sample of water is. The reality, however, is that an electrolysis tester is not a suitable way of testing water quality, as a basic understanding of the chemistry behind the process will underline. Continue reading our “What do you measure with an electrolysis tester?”-article to learn more if this testing method is useful.
What does an electrolysis tester do?
Electrolysis is the process of passing an electrical current through a liquid, resulting in a chemical reaction. The electrodes send an electrical current through the water sample. This current begins to break down the oxygen and hydrogen within the water. The water conducts electricity more easily because of the small quantity of salts and mineral that naturally occur within it, such as calcium and magnesium.
As well as the molecules within water, we also need to remember that the electrode itself is made of iron. This reacts with the salts and minerals in the water, oxidising to form ferric hydroxide – commonly known as rust. This rust is the source of the horrible brown sludge that is sometimes said to “prove” how contaminated your water is.
Except, of course, it doesn’t. The rust forms because of the combination of salts and minerals, the hydrogen and oxygen in the water itself, the iron on the electrode, and the electrons of the electric current. The unsightly brown “sludge” is a product of chemistry and does not originate either from the water, nor its source and certainly not from your purification system!
How do the results differ between purified water and tap water?
An electrolysis test does not reveal anything about the quality of a water sample, nor does it indicate how your countertop water filter is performing. Instead, it demonstrates that a chemical reaction has taken place and is a good visual demonstration of the rusting process. If the “results” show a darker brown from one sample or the other, it is simply testament to a higher salt or mineral content.
Water which has been boiled and then recondensed to a liquid results in a sample which has a lower mineral content. This won’t conduct electricity as well, and so will result in a less rusting. Of course, distilled water is not the same thing as purified water. Purified water removes impurities and contaminants, which you can read more about over here. It is important to remember that minerals are vital for human health and for the pH and taste of water that we expect.
What minerals might be in my water sample?
Water is full of essential minerals, which are quite simply essential to human life! During the water cycle, if water has travelled over rocks such as limestone or chalk, it will absorb some of the minerals present within them. These include calcium and magnesium, which give water the taste we expect and slightly alter its pH. Water from different geological areas features a very slightly different mineral composition. These minerals are beneficial and therefore are not removed during the purification process. Ironically, undesirable contaminants such as micro plastics and microbes do not affect electrolysis – but thankfully are removed by your counter-top water filter!
An electrolysis tester is an impressive visual chemistry experiment, that demonstrates the rusting process quite dramatically. It doesn’t, however, tell you very much about the quality of your water sample though.
So, does it serve a purpose at all?
Well, yes and no. A water electrolysis tester in some cases can be helpful.
Don’t use this device if you try to “test” tap and/or filtered/purified water.
Do use this device in combination with distilled water. In addition, If you have a reverse osmosis water filter this device can be used to check if your device is working properly. Distilled water is a poor conductor of electricity. Therefore, no current flows and thus the electrode stays intact. Subsequently, the water sample stays perfectly clear.