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What makes Lake Rotomairewhenua of New Zealand the cleanest lake in the entire world? It compares to distilled water in its level of clarity and cleanliness. In my last post I covered the possibilities of UV radiation, decreased air pressure, freezing cold temperatures, and limited human interference. After a little digging, I found The Freshwater Project by Michel Roggo from Switzerland. Roggo is a photographer whose passion is photographing clear, beautiful waters.

Somehow Roggo managed to capture these waters even though they are protected from human touch. His site states that the National Institute of Water and Atmospheric Research and the Department of Environmental Conservation teamed up to do research on this lake. Water is fed into Rotomairewhenua from Lake Constance. Using google maps you can see that water travels a little over half a mile underground to get to Rotomairewhenua. Scientists came to the conclusion that because of the filtration of particles through the sediment in the ground, similarly to membrane filtration, the larger particles are sifted out and by the time water reaches its final destination, it is almost completely pure.

However, Roggo mentioned something on his website that had me wondering if maybe the lake wasn’t just clean because of membrane filtration. It had to be a combination of treatments like the ones I mentioned. Why? Because as early as 6 years ago, in 2010 the land was passed through ownership of the Maori people, who used it for post mortem rituals. Roggo states, “The lake was traditionally used in ceremonies to cleanse the bones and release the spirits of the dead, so they could begin their journey to Hawaiki, and the Iwi (Maori, people who migrated from Eastern Polynesia to New Zealand around 1300 AD) regard its waters as tapu (sacred). Blue Lake (Rotomairewhenua) was used only for males; Lake Constance was used for females”.

Based on this information, not only would Lake Constance bare waterborne bacteria from the dead, but Rotomairewhenua would also possess pathogenic bacteria. What this means is that diseases like Salmonella, Rubella, Hepatitis, perhaps even Legionnaire’s Disease, could have been thriving in the lake due to the post mortem exposure of certain bacteria to the water. There had to be something else keeping the water pure after all these years. How is this still the cleanest lake in the world? I think it’s time to take a second look at the Wonder Down Under.