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'''[[Iron oxide adsorption]]''' filters the water through a granular medium containing ferric oxide. Ferric oxide has a high affinity for adsorbing dissolved metals such as arsenic. The iron oxide medium eventually becomes saturated, and must be replaced. The sludge disposal is a problem here too.
'''[[Activated alumina]]''' is an adsorbent that effectively removes arsenic. Activated alumina columns connected to shallow tube wells in India and Bangladesh have successfully removed both As(III) and As(V) from groundwater for decades. Long-term column performance has been possible through the efforts of community-elected water committees that collect a local water tax for funding operations and maintenance.<ref>{{cite journal|last=SARKAR|first=S|coauthors=GUPTA, A, BISWAS, R, DEB, A, GREENLEAF, J, SENGUPTA, A|title=Well-head arsenic removal units in remote villages of Indian subcontinent: Field results and performance evaluation|journal=Water Research|date=1 May 2005|volume=39|issue=10|pages=2196–2206|doi=10.1016/j.watres.2005.04.002}}</ref> It has also been used to remove undesirably high concentrations of [[fluoride]].
'''[[Ion Exchange]]''' has long been used as a water-softening process, although usually on a single-home basis. Traditional anion exchange is effective in removing As(V), but not As (III), or [[arsenic trioxide]], which doesn't have a net charge. Effective long-term ion exchange removal of arsenic requires a trained operator to maintain the column.
