Arsenic
What you need to know.
Source
A raw water contaminant.
Arsenic is an element commonly found in soil, rock and sediment and its natural migration from the ground into raw water is typically the reason for arsenic contamination in private water supplies. As a problem that stems predominantly from natural buildup of the chemical in the earth, some areas of Scotland are more likely to experience problems with arsenic solely due to the makeup of the land. These areas include Kintyre, Islay, Arran, Galloway, the Southern Uplands and some parts of the mid-North Perthshire area, around Crieff.
In some cases, arsenic can be a problem that is introduced into the local environment by nearby activities. Arsenic is a common ingredient in pesticides and timber preservatives and can be a waste by-product in many industrial processes such as smelting or mining.
Key indicators
Hiding in plain sight.
Arsenic in water is both tasteless and odourless. There are also no visual indicators of arsenic contamination, such as staining, sediment or discolouration of the water.
The only way to confirm arsenic contamination is to conduct water testing.
Regulatory limit
Maximum level = 10μg/l
The regulatory limit for arsenic in drinking water is 10 micrograms per litre (10μg/l). Aligning with the health based guideline value set by the World Health Organisation (WHO), the limit ensures that the toxicity of arsenic to human health is minimised.
Arsenic and its compounds are known carcinogens, meaning that they are categorised as cancer causing chemicals. In light of this, while the limit remains at 10μg/l, governing bodies advise on reducing the risk of exposure as much as possible, so it is considered good practice to ensure that arsenic levels are reduced to the lowest concentration achievable by reasonable means.
Testing
Testing is essential.
Arsenic levels can naturally fluctuate over time, especially if new activities in the local environment introduce arsenic through waste or pollution. As fluctuations in arsenic concentrations will not produce any perceptible changes (for example, change in taste or smell), it is strongly advised that regular water testing is conducted to monitor arsenic levels.
Not only does regular water testing ensure peace of mind, but it also ensures that the water filtration system remains effective and that alterations can be made if necessary.