The Lowermoor water pollution incident occurred on 6 July 1988 at the South West Water Authority’s (SWWA) water treatment works at Lowermoor, near Camelford, Cornwall. A relief tanker driver discharged 20 tonnes of aluminium sulphate solution into the wrong tank at the unmanned works, subsequently contaminating water supplies to a large area of North Cornwall.

On the afternoon of Wednesday July 6 1988, a delivery of aluminium sulphate solution was made to the unmanned works. This was discharged into the wrong tank i.e. into the chlorine contact tank instead of into a storage tank. The start of the discharge was 5.03pm and it finished at 5.40pm. This tank is immediately upstream of the treated water reservoir for water awaiting distribution through the mains. Water contaminated with high concentrations of aluminium sulphate therefore moved into the treated water reservoir and then entered the distribution system.

Later on in the evening of 6 July, from about 8.00pm onwards, customers began to complain to SWWA that the water had an unpleasant taste and a sticky feel to the touch. These properties are consistent with water of low pH (acidic) and the presence of aluminium sulphate.

Ref: https://cot.food.gov.uk/sites/default/files/cot/lwpiapp811.pdf | Image Credit: BBC