DemographicsLiffey is approximately 97.06 square kilometres. In 2016 the population of Liffey was 155. The population is 55% male and 45% female. On average the monthly mortgage repayments in Liffey are $1000 to $1399. The most common weekly income bracket is $400 to $499 per week. Weekly rents in the area are on average $0 to $74.