You may come across this question in a pub quiz one day, or when being chased down by the Chaser, maybe!

Water as a compound, and water molecules are generally accepted as being made up of two hydrogen atoms and one oxygen atom (H2O). But not all hydrogen atoms are created equal. Hydrogen has three naturally occurring isotopes, or variants. These are: Protium, Deuterium and Tritium.

‘Ordinary water’ is mostly made up of the Protium isotope, 99.99%. However, it also contains a very low percentage of the Deuterium isotope (D2O). Approximately one in 6400 hydrogen atoms is Deuterium, equivalent to 156 parts per million (ppm). Trace amounts of the Tritium isotope contribute even less.

Water with a higher concentration of Deuterium is often referred to as ‘heavy water’, because of its higher density, attributable to one extra neutron. Heavy water can effect biological reactions, and be toxic to humans, but at concentrations exceeding 50%, compared with the usual 0.0156%.

Deuterium was first discovered in 1931 by Noble laureate Harold Urey, andlater used in 1934 in one of the first biological tracer experiments to estimate the turnover of water in the human body. Heavy water is also used in nuclear reactors, bringing stability to the fission reaction, but is itself not radioactive.

Bottled water producers regularly must disclose physical, chemical, biological and radiological composition and contaminants of their source water and finished product. However, Deuterium is not usually tested for. Bottled water generally though has Deuterium content between 135 and 158 ppm (Source: National institute of Health).

Deuterium composition of the following waters is available and published.

• Evian – 146 ppm
• San Pellegrino – 148 ppm
• Fiji Water – 149 ppm

Image courtesy of www.energy.gov.

Fluoride is derived from fluorite, the principal fluoride mineral in igneous rocks, formed through the solidification of magma or lava, and in some cases volcanic gases. Local councils may often add fluoride to municipal drinking water supplies as a ‘service’ to ratepayers. Excessive fluoride can cause mottling of tooth density in children. However, many health authorities champion small additions of fluoride for oral health. The recommended addition varies by market due to higher water consumption in warmer climates. In New Zealand the Ministry of Health recommends fluoride content for drinking water in the range of 0.7 to 1.0 mg/L or ppm. Fluoride may or may not occur naturally in mineral and spring waters, and generally only in low concentrations. For those wishing to avoid fluoride altogether, low or no fluoride waters ranged by aquadeli include: Acqua Panna, Antipodes, Aqua Pacific, Ararimu Natural, Ecowai, Evian, Font D’or, Malavella, Perrier and Santa Vittoria. Waters with low levels of naturally occurring fluoride, in parts per million (ppm), include: Ferrarelle (1), Fiji (0.24), Gerolsteiner (0.21), Otakiri (0.077), Parkers (0.11), Puits St Georges (0.5), San Pellegrino (0.55) and Vichy Catalan (1).

The alkalinity of water is decided by the minerals it contains. Alkaline minerals include calcium, magnesium, sodium and potassium. The higher the levels of these minerals, the more alkaline the water will be.

Alkaline water (as opposed to acidic water) has a pH of 7 and above. pH (“potential Hydrogen”) is a measure of acidity/alkalinity ranging from 0-14, with a pH of 7.0 being neutral. Our body’s blood and cells are naturally slightly alkaline (pH 7.4). However, the foods and beverages we consume tend to be acidic, upsetting the body’s natural balance. Consuming an alkaline water helps keep the body in equilibrium.

The NZ Drinking Water Standards guideline value for drinking water pH is 7-8.5. However, this doesn’t mean that drinking water outside these ranges is bad for you. Our bodies are very complex metabolically so it’s all about the balance of our diet as a whole, not a single component such as a glass of water. Bottled spring and mineral water generally ranges in pH from 5-10.

Adding a squeeze of lemon or lime juice to your water, as well as providing flavour, also increases your body’s alkalinity. This is because citrus fruits, even though they are considered culinary acids, are in fact metabolically alkaline once consumed.

Research shows that as we age, the ability of our kidneys to eliminate acids declines. In order to neutralise the increased levels of acid, the body compensates by taking alkaline minerals from other parts of the body, for example, by taking calcium from the bone.

Clinical studies show that supplying the body with alkaline minerals, as well as supporting our kidneys, also helps combat acidity in the connective tissues, thereby reducing inflammation and the pain that accompanies inflammatory conditions such as gout and arthritis.

Click here for some alkaline waters to try.