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Water treatment

Water from reservoirs needs a higher level of treatment than groundwater. We use a number of different processes to purify water to the high quality required by law.

The most common methods are sand filtration and dissolved air flotation where the water arriving at a treatment works flows through fine filters to remove algae, insects and any other objects.

Dissolved air flotation

Water is fed into a chamber where chemicals are added to make any particles stick together. Air is pushed up through the water forcing the particles to the surface where they are then removed.

Sand filtration

The water flows into fine sand filter beds which trap any remaining particles. The water is cleaned further by passing it through filters which trap any remaining particles.

In both methods filtered water is treated with lime to reduce acidity, and chlorine to kill any germs.


A small amount of chemical coagulant is added to help bind together any impurities so that they stick to the sand filters, which are cleaned regularly.

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