The water pan is for temperature, not humidity

It’s mostly about temperature stability, not adding moisture to the air.

The water pan in a charcoal smoker acts like a heat sink. Water takes a lot of energy to heat up and gives it back slowly when the fire dips. That smooths out temperature swings, which is the real win. The steam it produces does add some humidity, but in a sealed charcoal smoker you already have plenty of moisture from the meat and the fire. You’re not keeping ribs wet by having a pan of water — you’re keeping the cooking chamber from bouncing between 225 and 300.

For ribs specifically, humidity is overrated. They’re done in 5-6 hours, they have a decent fat cap, and spritzing or wrapping handles bark and moisture better than steam ever will. Just keep the water pan full with hot water (to avoid dropping temp when you refill) and don’t let it boil dry. If you forget to fill it, the ribs will be fine. The smoker might run hotter, so watch your temp.

Some people run sand or empty pans for different reasons. That’s fine too. But if you’re using water, you’re doing it for temp control, not rib moisture.

Ribs are forgiving. Focus on fire management and don’t stress the water pan.