Almost all modern reservoirs and rivers are contaminated with hazardous amounts of harmful impurities, especially for large cities. Treatment plants filter the river water, however drinking it in its pure form is still dangerous to humans. Therefore, where the purity of water is of particular importance, use purified distilled water. On its basis prepare medicines in pharmacies, you give her to drink to small children and people with vulnerable imunnitet. In addition, distilled water is essential to motorists, because only purified water can be poured into the batteries. So buy real distilled water is possible only in pharmacies and some shops. However, you need to check the quality of such a purchase.
Distilled water color, taste and smell virtually indistinguishable from water. To notice the smallest differences only in laboratory conditions using special instruments. However, it is known that pure water containing no impurities, can not conduct an electric current. That is why it is used for automotive batteries. Therefore, to test the quality of distilled water by using electrical devices.
Assemble the electrical circuit that connects the conventional charged battery and the light bulb led. Swipe contacts between circuit elements and lower the ends of the wires in the water so that they do not touch each other. If used water is purified from impurities, it will not be able to conduct electrical current, consequently, the discharge of the battery is not "ignite" the bulb of the led. Verify the operation of the electric circuit. If in a vessel with distilled water, you add a pinch of regular table salt and will conduct the same experiment with electrical circuit, the led light is "lit", received a charge from the battery.
When buying distilled water ask the seller a certificate of product quality and keep receipts.