What are the impurities found in tap water?

Water in nature is often regarded throughout the world as being totally 'pure', but this can be far from the truth. Even if a body of water is totally detached from any possible source of contamination from water flowing into it from rivers and streams, it will invariably be found to contain some chemicals and minerals because water is such a good solvent.

Limescale on a washing machine element

These chemicals can be drawn into the water by minerals and gases in the air, or eroded from the soil or rock. The integration of these dissolved materials are regarded as the ingredients that give water its title of 'pure water', which is actually a contradiction in terms, as water containing any form of foreign bodies, no matter how molecular can never be described as totally 'pure'.

The impurities that are found in water to give it its particular taste as well as causing such effects as hardness, caused by the presence of calcium or magnesium, colour, which is caused by the presence of iron in the water, going as far as possible poisoning caused by high concentrations of arsenic in the water or even radioactivity caused by the presence of radium.

Apart from these natural impurities that can gradually dissolve into water from its natural surroundings. There are also a number of forms of man-made contamination that can find their way into water. The most common are fertilisers and pesticides that can flow into water through overuse by the agricultural industry as well as toxic wastes and heavy metals from heavy industry.

On certain occasions, human effluent can leak into water systems through a fault in a sewage disposal system, However, and very thankfully, these occasions are few and far between.

The most common mineral impurities found in tap water are:

• Aluminum - Leached from the soil

• Arsenic - Leached from the soil

• Calcium - Leached from the soil

• Chlorine - Added as a disinfectant

• Copper - Leached from pipes

• Fluoride - Sometimes added for dental health

• Lead - Leached from underground pipes,

• Nitrates - Leached from the soil

• Phosphates - Leached from the soil/Agriculture

• Radium - From the breakdown of Radium-containing rocks

• Sodium - Leached from the soil/seawater

These are just a few of the more than 330* impurities that can be found in tap water. In most developed regions of the world water undergoes fairly high levels of filtration, and after which chlorine is introduced into the water in very low concentrations, making it suitable to use for most domestic applications. Water that has undergone a regular filtration process is known as potable water and can be drunk from the tap without excessive danger to health.

Tap water is inexpensive, but can still contain up to 800ppm of dissolved minerals and heavy metals as these are not removed during the filtration process. It is easy to see how over time, these minerals can build up and destroy heating elements in kettles and washing machines.

Distilled water is considered to be significantly more pure than tap water due to the process it undergoes during distillation. Distillation involves heating water to its boiling point, turning it into steam, and then cooling the steam back into liquid form. This process effectively separates water from the majority of its impurities, as most contaminants have different boiling points than water and are left behind during the vaporiaation stage.

Tap water, while generally treated and filtered by municipal water systems, can still contain a variety of impurities, such as minerals, heavy metals, chemicals, and even microorganisms. These impurities are not removed during standard filtration and disinfection processes that tap water undergoes before reaching your home. As a result, tap water will contain dissolved minerals and contaminants that can impact its taste, appearance, and safety for consumption.

In contrast, distilled water has been subjected to a more rigorous purification process, which is specifically designed to remove these contaminants. As water is heated and converted into steam during distillation, only the pure water molecules transition into the vapour phase, while most impurities are left behind. When the steam is cooled and condensed back into liquid form, the resulting water is significantly purer than before, with a majority of contaminants having been removed. This makes distilled water an ideal choice for applications that require high purity levels, such as medical, laboratory, and industrial uses, as well as for those who seek the purest form of water for drinking and cooking purposes.

*source: https://www.opencollege.info/do-you-know-whats-in-your-tap-water/