Don't fill this with water (if you don't cap it tightly, it leaks). I used sand. all purpose sand works well. I also used sand from sand bags tubes. I cut a water bottle in half to use the spout. A common water bottle spout fits inside the opening with ease, and stays put as you pour sand into the base. Each segment will become heavy when using sand. My umbrella stood up to a 40mph gust of wind with no problems. Didn't even budge in the slightest.