Risers are a vital but often misunderstood part of a building's fire protection. They give firefighters a way to get water to the upper floors quickly, without running hoses all the way up the stairs. There are two types, dry and wet, and knowing the difference matters for compliance and maintenance. Here is a clear comparison.
What is a riser?
A riser is a system of pipework running vertically through a building, with outlets (landing valves) on each floor, that lets the fire service connect hoses and deliver water at height. It saves crucial time during a fire and means firefighters do not have to haul hoses up through the building.
Dry risers
A dry riser is empty of water until it is needed. In a fire, the fire service connects a pump, usually a fire engine, to an inlet at ground level and charges the pipework with water, which then comes out of the landing valves on each floor. Dry risers are used in buildings between 18 and 50 metres in height. Because they are normally empty, there is no risk of freezing or leaks, but they rely entirely on the fire service to supply water. If water does get into one, a flooded riser inspection will find the cause before it does damage.
Wet risers
A wet riser is permanently charged with water, fed by a tank and pump within the building, so water is available at the landing valves immediately. Wet risers are used in buildings over 50 metres, where the height is too great for a fire engine to pump reliably. Because they hold water under pressure at all times, they need more maintenance and monitoring than dry risers.
The key differences at a glance
- Water: dry risers are empty until charged by the fire service; wet risers are always full.
- Building height: dry risers for buildings 18 to 50 metres; wet risers for buildings over 50 metres.
- Water source: dry risers rely on a fire service pump; wet risers have a built-in tank and pump.
- Maintenance: both need regular testing, but wet risers require more because they are permanently pressurised.
Testing and maintenance
Both types must be tested and maintained to stay reliable and compliant. Dry risers are typically subject to a visual check and an annual wet pressure test. Wet risers need regular inspection of pumps, tanks and pressures alongside annual testing. Faulty landing valves, leaking seals and pressure problems are common issues that regular maintenance catches before they matter. Our guide to what is involved in an annual dry riser test covers the yearly test step by step.
Which do you need?
The right system depends mainly on building height, but layout and water supply also play a part. If you are designing a building, refurbishing one, or unsure whether your existing dry or wet riser is being maintained properly, contact Eversafe for a free assessment.
Frequently asked questions
What is the main difference between a dry and wet riser?
A dry riser is empty until the fire service charges it with water, while a wet riser is permanently filled and pressurised by a built-in tank and pump.
When is a wet riser required instead of a dry riser?
Wet risers are used in buildings over 50 metres tall, where a fire engine cannot reliably pump water to the top. Dry risers are used between 18 and 50 metres.
How often should risers be tested?
Both need regular inspection and an annual test. Wet risers require more frequent checks because they are always under pressure.