Work out how much it costs to keep them at homeCalculations for The Mail on Sunday by wealth manager Quilter found that it costs £3,246 a year in food, energy and water bills to have an adult child living at home. Water bills vary by region but the number of people living in a home can have an impact, too. They will need to save up enough for a deposit to rent a property or to buy one. Let us know: Lucy.evans@mailonsunday.co.ukWe asked our daughter, 22, to pay £50 a weekPaul O’Brien, 50, and his wife Lorraine, 45, of Uxbridge in west London, have plenty of experience of adult children living at home. ‘You do what you can for your children but without them my food and utility bills were lower,’ she says.