Good Canopy for rainy days

We use an EZ-Up brand. Like most others, it will collect water in the sag of the fabric. So I use four Gator-clip type "clamps" that latch onto the bottom edge of the fabric tarp overhang in the middle of the span, then connect the two clips opposite each other with by-the-foot bungee cord (like a piece of rope, just stretchy). Do the other two clips the same way, so you have two bungee cords crossing each other in the center of the shelter. This tensions the tarp so that there is no sag to pool the water. On mine I also ran a bungee cord from the middle of each cross-beam up to the top of the post to provide an extra ridge all the way down the length of the tarp.

Some day I plan to replace the Gator-clips with sewn-on loops of webbing to provide attachment points for the bungee cord, just to neaten things up, but so far they have worked just fine.

Good luck!
Regan