Book 30, Question 98
Why do some towns limit when you can water your lawn?
In summer, lots of people water their lawns at the same time, and the demand can be bigger than the water system can handle.
Pressure drops, and there may not be enough left for fire hydrants or drinking. So some towns set watering days or hours, such as only in the early morning or evening. Watering then loses less water to evaporation. These rules are called watering restrictions.