Lifespan Spring Water, the Portland-based bottled-water company now marking its 21st anniversary, has grown from a modest start-up in rural Jamaica into a regional brand with international reach. According to chief executive officer, Nayana Williams, the company’s progress over the past two decades has been the result of sheer resilience. Lifespan’s naturally alkaline spring water, measuring 7.9 to 8.4 on the pH scale, has earned more than seven international awards.