Watering question

[Big Red Hen]

About how much water should nearly 11 wk. old Leghorn pullets drink? Currently, they're drinking about 1/2 gallon of water.

 

[Cats Critters]

They should have water 24/7, they will know when they have had their fill.

 

[Davaroo]

Thasss right. They should always have clean, fresh water and you should clean and ensure their waterers are full (or working, in the case of auto-fountains) daily. You can regulate their feeding - but never stint on the water.

Leghorns will drink a bit less, due to reduced body size. But they are egg machines and the egg is mostly water. Smaller body + more eggs = plenty water.
In general, layers drink about twice as much water, in pounds, as they consume in feed. 1-2 inches of water access is needed per bird.
Temperature has an effect, too. The hotter it gets the more water they drink:

Temperature Gallons h20 consumed/100 birds
20-40................................................4.2-5.0
41-60................................................5.0-5.8
61-80.................................................5.8-7.0
81-100................................................7.0-11.6

source: N. England Poultry Management and Business Analysis Manual, bulletin 566.