Dry riser and wet riser systems are both crucial fire safety features in buildings, but they differ in how they supply water. Dry risers are empty until needed, requiring firefighters to connect to an external water source during a fire, while wet risers are constantly filled with water, offering immediate access for fire suppression. 
Dry Riser System:

• Suitable for:
  Buildings up to a certain height, often up to 18 meters (around 60 feet). 

• Advantages:
  Lower risk of water damage from leaks, potentially lower installation costs. 

• Disadvantages:
  Requires firefighters to connect to an external water source during a fire, which can cause a delay. 

• Function:
  A system of pipes and valves installed in a building, typically for fire service access to upper floors, but kept empty until needed. 
• Water Supply:
  Firefighters connect to a breeching inlet at ground level to supply water to the system. 

Wet Riser System:

• Function: A system of pipes and valves that are permanently filled with water, often pressurized by pumps. 

• Water Supply: Continuously holds water, readily available for fire suppression. 

• Suitable for: Taller buildings, where immediate water access is critical. 

• Advantages: Provides instant access to a water supply, allowing for a faster response to fires. 

• Disadvantages: Higher risk of water damage from leaks or pipe failures.