Relatively low manganese levels in water can result in tainting of taste as well as discoloration of the water and the surfaces it comes into contact with. The Drinking Water Inspectorate (DWI) in the United Kingdom have set a maximum allowable limit of 50ppb, well below the WHO guidelines of 400ppb. While the WHO regulations are based on health concerns of the bioavailable form of manganese the DWI regulations are concerned with providing drinking water at the point of use which also looks healthy and tastes good i.e. free from discolouration and taint.
The 50ppb limit set by the DWI was intended to ensure that discolouration and taste tainting was acceptable to the consumer. However, recent studies conducted by Welsh Water and Severn Trent have shown that levels as low as 2ppb can still be problematic at the point of use.
Flushing pipework to remove the contamination on a regular basis is time consuming, disruptive to the consumer and expensive. In an attempt to develop a more viable treatment system that can produce water with a manganese concentration below 2ppb Welsh Water partnered with Amazon Filters Ltd to look at an