If arsenic can be reduced in water supplies, why is it a world wide water problem?
The first problem is knowing that it is there: this means testing water supplies. Apart from the cost of testing, someone has to be responsible for making sure the testing is done: this can be a problem in small supplies such as a village well. Education, training and monitoring are expensive and this is one of the greatest problems in controlling arsenic contamination and its effects. The cost can be kept down by restricting the testing to water used for drinking purposes: arsenic contaminated water may be used safely for bathing and laundry purposes. Quality control—making sure the analysis is correct—is also important. While chemical or filtration treatment is effective, there can be problems in the use of chemicals to remove arsenic. For example, alum (aluminium sulphate) requires prolonged contact with the water to remove sufficient arsenic, which may be difficult in supplies without a water treatment works. Letting the water settle helps in iron rich waters, but only a proportion
