Most of the drinking water for our cities and towns comes from densely forested catchments in nearby mountains. These catchments act like large, and very cost effective water treatment plants, slowly filtering rainfall through the soil before releasing clean water back to rivers and reservoirs.
In fact, this natural water filtration system is so effective that very little additional treatment is required, which minimises the need for large and expensive water treatment plants.
However, while this fortunate situation provides a very low-cost source of water, it also creates a vulnerability in our water supply system.
More often than not, our Australian catchments are vegetated with highly flammable Eucalyptus forests. A bushfire in a catchment can have major impacts on water supply; heating from the fire causes the soil to become hydrophobic (water-fearing), while the loss of vegetation exposes the soils, greatly accelerating soil erosion.
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