Water chemical tests strips
Test strips are quite handy to quickly test some chemical properties of water, soil, or even air and some food. If a specific compound is present a chemical reaction takes place and the strip test area changes color. The resulting color can then be compared to the scale provided with the test. Specific shade can be assigned to a concentration of the tested compound.
So with a simple color change we can test how acidic or alkaline the water sample is, or what's the hardiness level, so we can optimize detergent and softener amount when doing laundry.
As you can see there are a lot of different test strips and those three are just one of many. As shown, some are used to test aquarium water as some fish species are very reliant on water parameters to be just right. Next, we have pool water tests which often use chlorine or bromine to disinfect the water. The last one is generic targeting multiple compounds.
Water hardness and carbonate root is a measure of the amount of dissolved calcium and magnesium ions in the water. Nitrate and nitrite ions can be found in open or aquarium water and it comes from the natural nitrogen cycle or fertilizers. You don't want that in drinking water.
pH is a scale used to specify the acidity or basicity of an aqueous solution while alkalinity is the capacity of water to resist acidification. Water going through limestone and other carbonate rocks will pick up carbonate, calcium, magnesium, and other ions which will increase its hardness, pH, and alkalinity. Such water is then pumped out and bottled as mineral water.
Iron, copper or lead ions in water are usually a sign of contamination. Old pipes could be welded with lead while the pipes themselves often are made out of copper. If the incoming water is for example acidic it can start corroding such metals leading to water pollution. Iron can also come from iron-rich deposits through which water seeps down. In any case, if your tap water shows any signs of such contamination you should contact local services/authorities.
To check if the tests are accurate I've used distilled water and local mineral water coming from a limestone-rich area:
And as expected distilled water got a more neutral pH, alkalinity, and hardness at zero. No chlorine, or metal ions. Local tap water results were also in line with expectations:
The hardness of local water is a bit lower than the mineral water source I've picked. No metal contamination.