Tap water composition

Water is essential for human life and hence a primary concern for space settlements. Pure or demineralized water is not suitable for human consumption. Therefore the composition of tap water is of great importance.


Hard water is water that is rich in calcium (and magnesium) carbonates. The higher the concentration of this substances the greater the “hardness” of water. Though there appear to be little to no negative effects on human health, hard water does have some serious.

Scaling, calcium caused fouling, cause the clogging of pipe lines, corrosion in all kind of water using household appliances and reduces the thermal capacity of water. In turn this results in higher energy costs and shorter life time of domestic devices.

Therefore we favor, in line with scientific recommendations, a low concentration of calcium and magnesium carbonates in tap water of about 2 mmol/L. And to prevent the destruction of pipe lines due to “aggressive water” we suggest the use of polymer water tubes as method of transportation.


Chlorine is added in many countries to disinfect tap water, but it gives water a bad taste. However, water disinfection could also be achieved by the use of ozone or UV radiation. The main benefits of these methods is that they do not affect the taste of water at all.

A major reason for the bottled water industry is the bad taste of chlorine in water. By opting for alternative disinfection methods the demand for bottled water would diminish and hence reduce the negative environmental impact of bottled water.


Water fluoridation is a policy used by some governments as a tool to prevent tooth decay. Though it is an effective method as it reach a large amount of people, it is simultaneously rather inefficient.

An average human consumes about two liter of water a day. However, clean water is not only used for personal consumption but also for dish and clothes washing, showers and so on. A typical 8 minute shower uses about 65 liter of water.

Let’s say that an average person uses about 100 liter of clean water a day – a rather conservative estimate, only two percent is actually used for bodily consumption. Or put it differently, at least 98 percent of the fluoride added will be wasted.

There are alternatives to water fluoridation such a fluoridated toothpaste and mouthwash – and we would prefer the subsidization of those methods as they would result in less fluoride waste.


Lithium is a known psychiatric drug and is used to treat depressions and hence there has been proposals to add a little amount of lithium to tap water as measure to prevent suicide. Some studies show that there is a correlation between lithium concentration and suicide rates, with higher lithium concentrations linked to lower suicide rates.

However, correlation does not equal causation and other studies give reasonable doubt to the claim that adding lithium could save people’s lives. Also there are studies that suggest that a higher concentration of lithium in tap water could cause dementia, whereas a moderate concentration could prevent dementia.

Since scientific research give conflicting results, we believe tap water companies should be very careful when considering adding lithium to tap water.

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