Monday, October 12, 2009

New Zealand Drinking Water - Best in the World? - Part 2

So I've come up with the following information from my research on the drinking water in Christchurch (recall that I first was curious about it in this post):

- The water does not need filtration or chlorination. This means that there is no chlorine residual in the distribution system though, so they sample more frequently to ensure there isn't any contamination somewhere there. [Source]

- The water has a really low hardness; this explains the really soft water. Maybe I just imagined the whole "ground source makes it hard" explanation. [Source]

- Gravel and sand layers created from glaciers and rivers provide natural filtration to deep confined aquifers below. [Source]
*I wonder how deep the aquifer is, there has to be a confining layer somewhere otherwise contamination would be too easy. Gravel and sand aren't aquitards, but it could be that an advancing and retreating glacier system deposited gravels and sands and then clays and silts as the movement got slower.

So, my research thus far has led me to more questions:
What is it that makes Canadian groundwater harder? We had glaciers in Canada too, why is our water brimming with contamination that we need to chlorinate it? Are the standards different?

2 comments:

  1. Hardness in water is due to mineral content, mainly calcium and magnesium. Ground sources are mostly hard, which is why you thought that, but it depends on how the soil has formed. Calcium is mostly from limestone, magnesium is mainly from dolomite. Waterloo's water is mostly from ground sources, and is super hard due to the high mineral content in the soil. Check it: http://en.wikipedia.org/wiki/Hard_water

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  2. wow sylvie you're my hero. i figured there was a simple answer but i guess you paid more attention in class than I did! I remember seeing huge limestone rocks in the plains though, but maybe during the glaciation or soil formation there wasn't a lot of limestone and dolomite.

    I could understand if most of the water was from reservoirs as they would be fed from mountain lakes and glacier melt. I'll have to look up soil formation in New Zealand and write another post!

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