Splash it around to make things wet. It can also scoop up water, though there's a good chance you'll just spill it. Butterfingers.
Water Bucket price in Growtopia: sells for about 50/WL, buyers pay about 40/WL (median of 335 offers from community Discords, past 30 days). Live price chart and the latest buy and sell offers.
Recently sold at: NANSX, MISSIONST, TUZOL, EJEN, CIPSAN9