Investment in a removal plant has to be considered against the cost of a deeper borehole tapping arsenic-free water. It is also likely that in the long term, the acceptable limit for arsenic will be lowered to the WHO standard, which will tend to make treatment more difficult and expensive in addition to being required in more areas than at present. Surface water will require treatment to remove suspended solids and ensure that it is biologically pure. Simple filtration systems, such as pond sand filters, can be effective, but require very frequent and careful maintenance. However, the capacity of existing ponds is limited and they are privately owned.
New ponds require land.
Consumers who have their own pumps are reluctant to revert to using a shared source. The number of rivers which have reliable dry season flaws are limited. During low flow conditions these may contain relatively high concentrations of agricultural or industrial chemicals, which are very expensive to remove. Current information indicates that the risk of arsenic occurring in groundwater drawn at a depth of 300rn is very low. The iron content also tends to be lower at this depth compared with shallower water, although the hardness may be higher.