Songkran was traditionally the time when Thais poured water on statues of Buddha to refresh and clean them, and then captured that water to pour on their elders as a sign of respect. It’s a time of renewal and reflection, and of looking forward to the rain that comes soon after the New Year is properly celebrated. Houses are cleaned, Buddha is given a good scrubbing, and everyone goes to the temple to make plenty of merit by giving food and supplies to the monks.
Fast forward a couple hundred years, and Songkran has become less about renewal and reflection and more about getting people wet during the hottest part of the year. Preparation is essential.