If your horse has a herd mate who she looks up to who is not afraid of water, show her how the other horse is not afraid of the water. You can also try leading them through the water together to reduce anxiety.
Slow and easy. Apply pressure for her to come toward the water and with a step toward it, release and praise. Keep doing this for a little while and release/praise. If she still refuses then lunge her beside the puddles both ways until she is relaxed. Then try the pressure and release again. Your ultimate goal should be for her to put her nose to the water. If this happens instantly release and praise and work on something else to give her mind a break. Come back to it and try again until she takes one step into the water. Praise!! Then two steps then 3 etc. Try to lunge her through it after she stands in it. This will take time!!! Just praise as much as possible. Use your voice to let her know it's okay! Hope this helps! Good luck!