There is no safe substitute for saline contact solution, according to All About Vision and Dr. Elliott Rosengarten. Some people use tap water or bottled water to clean contact lenses, but water carries microorganisms that may lead to serious eye infections. Baby oil and fruit juice are other bad choices.
Elliott Rosengarten reports that people should even clean lenses with saline solution if they get water on them. In lieu of a substitute cleaning solution, All About Vision advises people to always take care to carry solution or wear disposable contacts. With disposable contacts, a person can just throw out the lenses if they become dirty or contaminated.