Bacterial, yeast and fungal spores are naturally present in the environment. These airborne spores can attach to damp surfaces, multiplying to form a visible slime or stain. These growths, more commonly known as moulds can vary in colour from dark brown and black through to orange and pink and can grow on any damp surface but are most commonly seen:

• On the inside of coldwater taps
• In toilet cisterns and toilet bowls
• On tiles in the bathroom and shower room
• On showerheads and shower curtains
• In the powder drawer of washing machines.

Although they do not look very pleasant they are generally harmless, posing no risk to health and are not caused by a deficiency in your water supply.

These spores like warm damp environments to grow in and substances such as soaps, shampoos, hair sprays and deodorants provide nutrients for these types of growth. Improving the ventilation in areas where moulds are developing and rinsing surfaces free of soaps and shampoos will help to minimise the problem.

In coldwater taps, moulds can build up to form a black sludge that can appear from the tap spout. This type of growth can be made worse if the tap is fitted with a plastic insert. These inserts retain moisture and provide a bigger surface area for moulds to grow on. Rough surfaces such as limescale can also increase the rate at which these moulds attach and develop. Limescale can be removed using a solution of sodium bicarbonate or a proprietary cleaning product.

Regular cleaning of the inside and outside surfaces of the taps with a mild bleach solution can help to reduce this problem. Taps used for drinking and cooking purposes should be run for a few moments to remove any disinfectant.