Do you want to drown your compost in water?

Answer 1

Never, composting is an aerobic process, meaning the bacteria responsible for it need air, or rather oxygen. These bacteria will also generate lots of heat, as high as 70 °C / 158 °F for horse manure, which also help sterilizing the compost and keeping the "bad" bacteria away.

The compost heap needs to stay moist though, so some light watering will benefit it in summer, but the best is to cover the heap with a "mulch" of straw, grass trimmings, leaves, cardboard, whatever is available and biodegradable and lets the air through. This will ensure that the compost stays moist inside.

If you are using a composting bin, watering is rarely needed.

Most professionals put compost heaps on a grid, so that the large heaps that cannot be ventilated from the sides, can get air from the bottom.

Mixing the compost heap inside out regularly is as important than watering.

Toxic anaerobic bacteria must be avoided, so keep your compost well aerated.