Water Quality FAQs: Appearance of water

Why do I have a brown/black line in my plastic kettle?

Overtime minute traces of copper (which is an essential element that naturally occurs in water) become trapped within plastic materials used to manufacture a kettle. When these traces then comes into contact with oxygen inside the kettle they undergoes a process called oxidation, turning them black.

It can be washed out using a weak acid solution, such as a kettle descaler, readily available in most supermarkets and online retailers. These are not harmful when used in accordance with the manufacturer’s instructions.



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Uncontrolled if downloaded. This is informative, non-statutory guidance and intended for general guidance purposes only; it is subject to change.

Compliance with this information should not be relied upon as guaranteeing no enforcement action will be taken by water undertakers. Water Regs UK accepts no liability for loss, indirect or consequential loss arising from or in connection with this guidance document.