Like many other countries, Iran has numerous regions with high levels of geogenic arsenic (As) in groundwater which jeopardize safe drinking water supply in these areas. In an effort to address this problem in Iran’s Kerman Province, a large-scale drinking water dearsenification plant was erected at a waterworks there. The plant, which utilizes ferric hydroxide adsorption beds making it the first of its kind in the country, has now been in operation for over two years’ time. Due to the relatively high As content of the groundwater treated, the plant had to be designed with a combined process approach to realize optimum treatment performance. The process configuration selected, comprising (a) pH reduction of the inlet raw water, (b) multiple adsorber lines operated in parallel with time-staggered adsorbent exchange and (c) lead/lag configured beds and a standby bed making up each line, permits realization of long bed life of the adsorbent media used.