A wet hydrant system keeps its pipes permanently filled with pressurised water, so water flows the moment a valve opens. A dry system keeps its pipes empty until the fire brigade pumps water in. In Bangladesh's warm climate, where pipes never freeze, most buildings use a wet system fed by fire pumps and a water reserve.
How does a wet hydrant system work?
A wet system has four main parts:
- Water reserve: an underground or overhead tank sized for the required firefighting duration.
- Fire pump set: usually a main electric pump, a backup (often diesel) and a small jockey pump that keeps the system pressurised. See our fire pump guide.
- Pipework and risers: pipes that carry water around the site and up through the building.
- Outlets: landing valves and hose reels on each floor, and external hydrants around the site.
When someone opens a valve, the pressure drops, the pump starts and water reaches the hose within seconds. NFPA 14 covers standpipe and hose systems like these.
How does a dry system work?
A dry riser is an empty pipe with an inlet at ground level and outlets on each floor. When firefighters arrive they connect their pump to the inlet and charge the riser. Dry systems are used where pipes could freeze, or as a dedicated connection for the fire brigade alongside other protection.
Wet vs dry: the key differences
| Wet system | Dry system | |
|---|---|---|
| Water in the pipe | Always | Only when the fire brigade charges it |
| Water available | Immediately | After the brigade connects |
| Needs fire pumps and tank | Yes | No (uses the brigade's pump) |
| Usable by occupants | Yes, with hose reels | No, firefighters only |
| Best suited to | Warm climates, buildings that need first-aid firefighting | Freezing climates, brigade access points |
Which should you choose?
For factories, warehouses, malls and high-rises in Bangladesh, a wet system is usually the right answer: trained staff can start fighting a fire before the brigade arrives, and a garment factory or warehouse can burn fast. Many sites also add a fire brigade inlet so the brigade can boost the supply.
The exact requirement for your building depends on its use, height and area, and on BNBC 2020 and the fire safety plan. Check it at design stage, because the tank and pump room need space.
What affects the cost of a hydrant system?
We don't publish one price, because two hydrant systems can differ several times over. These factors set it:
- Building height and floor area, which set pipe lengths and the number of outlets.
- Required flow and pressure, which set the pump size.
- Whether the pumps are UL/FM listed.
- Water reserve: an existing tank, or a new one to build.
- Pipe material and the complexity of the routing.
- Whether a sprinkler system shares the same pumps.
A site survey turns these into a firm quotation.
How do you keep a hydrant system ready?
Check valves, hoses and gauges monthly, run the pumps on schedule, and flow-test the system at least yearly, following NFPA 25. Keep dated records. Our maintenance checklist covers the full routine.
Book a hydrant survey and we will size the system for your building.