1.
Lay wire 1.2 meter (4 feet) from the water edge.
2.
In case it is a seasonal puddle created by rain, take extra caution, and lay the wire even farther away, based on your experience with your lawn.
3.
Another option is to erect a physical barrier around the water hazard, such as a fence, at least 15cm (6 inches) high. The RT must not drive into the puddle or any water hazard.