| Bowl ||
|| | | ||
|| \ / ||
|-++-| |-++-| |-++-|
/ || \ / || \ / || \
/ || \ / || \ / || \
/ \ / || \ / \
| _____|_______| || |___________|____ |
| / ____________ || _______________ \ |
| |/ |Tubing | || | Tubing | \ | |
|----||----| | || | |----||----|
| || | | || | | || |
| || | | || | | || |
| || | |----||----| | || | D2
| || | | || | | || |
| || | | || | D1 | || |
| || | | || | | || |
\________/ \________/ \________/
Secondary Primary Secondary
D1 = water depth in main chamber (may be Zero)
D2 = water depth in secondary chambers (d2 > d1)]

This design requires no stoppers or valves -- it uses water pressure differences to affect a one-way valve.
The main requirement is that the water levels in the secondary chambers are higher than the water level in the primary
chamber. This allows the bong to work even without every "service station" occupied!