Water in the growing material, water vapour in the room air and liquid water on a mushroom surface are different observations. A humid room does not prove that the material contains enough water. A wet cap does not prove that the crop needs more mist.
Before adding water, identify the crop stage and material you intend to affect. Record the previous application and inspect representative locations using the method taught for that crop. Consider recent changes in temperature, ventilation and surface drying.
Also include the supply itself in the farm plan: source, storage, distribution, cleaning and any testing required for its intended use. Clear-looking water is not evidence that it is suitable for food-contact or cultivation operations. Use the applicable trained procedure rather than a universal daily litre figure.