The most likely cause of pink coloured staining is an airborne bacterium called Serratia Marcescens which is common in both the UK and abroad and generally grows in damp conditions such as bathrooms and kitchens. The bacteria produce a pinkish film on surfaces that are regularly moist including toilet bowls, showerheads, sink drains and tiles. Serratia Mercescens thrive on moisture, dust and phosphates and have been found naturally in soil, food and also in animals.

Often the pinkish film appears during and after new construction or activities such as the replacement of bathroom fittings. Once airborne the bacteria seek moist environments to multiply. These airborne bacteria can come from many naturally occurring sources and the condition may worsen if customers remove the chlorine from their water by using activated carbon filters.

What to do

The best solution to keep the surfaces free from the bacterial film is regular cleaning. Chlorinous substances are best, but avoid using abrasive cleaning products which could cause rough surfaces to develop and encourage bacteria to take hold. 

  • periodically stir chlorine bleach into the toilet cistern
  • keep bathtubs and sinks wiped down and dry
  • a disinfectant containing toilet block can be placed in the cistern

Cleaning and flushing with chlorine will not necessarily eliminate the problem but will help to control the pink bacteria.