‘The water’s gone pink’. Why we all need to think before we flush

A recent oversight at a water treatment plant in Canada resulted in the town of Onoway being the surprised recipient of fuschia pink water (as shown in the picture above). The pink colouration was the result of the accidental inclusion of low levels of potassium permanganate in the water distribution system.

This was not harmful because potassium permanganate is a chemical disinfectant that is commonly used to remove the 'rotten egg' smell from wastewater during treatment. In this case, it appears that a faulty valve caused potassium permanganate to leak from 'normal line flushing and filter backwashing' to the water distribution system. Nonetheless, residents were initially concerned and puzzled, and the water utility apologised for not letting residents know earlier.

Invisible pollutants from domestic customers

This unusual incident is a reminder that the process of wastewater treatment involves both adding and removing chemicals from water. This process is usually invisible to domestic customers. For most, this process is 'out of sight, out of mind'.

At ICE's seminar on UK water supply issues at Ecobuild 2017 one participant raised a question about the often neglected topic of 'pharmaceutical pollution'. They weren't referring to wastewater from pharmaceutical firms but domestic consumers flushing away unwanted medicines at home.

Financial costs and long-term harm to human health

Disposing of unwanted medicines has negative and costly effects for our water supply systems. It requires expensive waste water treatment processes so that residues of pharmaceutical pollution are removed from the water supply.

In addition, longer term it also has negative consequences for human health. Domestic pharmaceutical pollution has undesirable effects in other parts of the water system, such as increased antibiotic resistance due to the release of antibiotics outside of supervised clinical or veterinary need, or the accumulation of medicinal compounds in non-human organisms such as fish. For instance, there are concerns about the long term effects of elevated levels of some artificial hormones in river water on fish.

Time to stop flushing the tablets

The often invisible work of waste water engineers needs greater recognition as well as the unnecessary costs incurred by misuse of domestic water supplies for waste disposal.

Most importantly, we need to shout louder and stop people at home flushing the tablets down the loo.