Lewiston is a semi-rural locality in South Australia, 6 km east of Two Wells, 12 km west of Gawler and 56 km from the Adelaide city centre. At th…Lewiston is a semi-rural locality in South Australia, 6 km east of Two Wells, 12 km west of Gawler and 56 km from the Adelaide city centre. At the 2011 census, Lewiston had a population of 2,947. Lewiston is an animal and crop farming area.