Essentially no watering. Only works with places with some mild temps, a 20 inches of rain per year, and some morning fog etc.

Where appropriate climate and soil conditions exist, growing dry-farmed tomatoes can be a good option for specialty crops growers. Dry farming generates an intensely flavored crop much prized by consumers and retailers.

A limited number of geographic regions are suited to dry farming, which requires adequate winter rainfall and—in the case of annual crops—a summer-time marine influence that generates cool mornings and warm afternoons. These climatic conditions, combined with careful soil preparation, appropriate variety selection, adequate plant spacing, and vigilant weed control are all required to successfully produce dry-farmed crops.

https://agroecology.ucsc.edu/resources/publications/grower-guides/pdf-downloads/dry-farmed-tomatoes.pdf