40+ Years of Proven High-Pressure Performance

The WATERAX BB-4® series has been the weapon of choice for forest agencies and wildland firefighters for over 40 years. These high-pressure 4-stage centrifugal pumps deliver the pressure needed to operate very long hose lays and overcome pressure losses due to large elevation changes encountered in rugged wildland fire operations.

Available with 18-23 HP Briggs & Stratton Vanguard, 21 HP Honda GX630, or 25 HP Kubota diesel engines, BB-4 pumps deliver pressures up to 440 PSI and flows up to 106 GPM. The innovative quick-release clamp allows field replacement of pump ends in minutes without tools.

The 4-stage pump end on the BB-4 is identical to the pump end on the legendary MARK-3®, greatly reducing spare parts inventory and improving response to unexpected equipment damage. You can also quickly install a mid-range B2X™ pump end as needed for supply or structure firefighting.

Key Features

  • MARK-3® Compatible Pump End

    The 4-stage pump end is identical to the MARK-3®, reducing spare parts inventory. The quick-release clamp allows field replacement without tools, minimizing equipment downtime.

  • Maintenance-Free Bearings

    Sealed ball bearings eliminate pump end greasing in the field. Combined with the blister-resistant mechanical rotary seal, BB-4 pumps deliver extended service life in demanding conditions.

  • Belt Drive System

    Proven timing belt and pulley system with 1.88:1 speed increaser provides reliable, low-maintenance power transfer. Time-tested over 40+ years of field use by forest agencies worldwide.

Choose Your BB-4 Configuration

The BB-4 series offers multiple engine options to match your power requirements: Briggs & Stratton Vanguard (18 or 23 HP), Honda GX630 (21 HP), or Kubota diesel (25 HP). All models share the same proven 4-stage pump end.

BB-4-18 (18 HP Briggs & Stratton)

  • BB-4-18 Performance

    Maximum Pressure: 440 PSI (30.3 BAR)
    Maximum Flow: 104 GPM (394 L/min)
    Maximum Head: 1,016 ft (310 m)
    Pump Type: 4-stage centrifugal

  • BB-4-18 Flow at Pressure

    At 150 PSI: 100 GPM (379 L/min)
    At 250 PSI: 80 GPM (303 L/min)
    At 350 PSI: 50 GPM (189 L/min)

  • BB-4-18 Configurations

    BB-4-18V: Vehicle mount, vertical drive
    BB-4-18VT: Vehicle mount with integral fuel tank
    BB-4-18VX: Vehicle mount with exhaust primer
    Weight: 153-165 lbs depending on configuration

    Shop BB-4-18 

BB-4-23 (23 HP Briggs & Stratton)

  • BB-4-23 Performance

    Maximum Pressure: 440 PSI (30.3 BAR)
    Maximum Flow: 106 GPM (401 L/min)
    Maximum Head: 1,016 ft (310 m)
    Pump Type: 4-stage centrifugal

  • BB-4-23 Flow at Pressure

    At 150 PSI: 105 GPM (397 L/min)
    At 250 PSI: 95 GPM (360 L/min)
    At 350 PSI: 65 GPM (246 L/min)

  • BB-4-23 Configurations

    BB-4-23V: Vehicle mount, vertical drive
    BB-4-23VX: Vehicle mount with exhaust primer
    BB-4-23PXTC: Portable with carry frame
    Weight: 153-162 lbs depending on configuration

    Shop BB-4-23 

BB-4-21H (21 HP Honda GX630)

  • BB-4-21H Performance

    Maximum Pressure: 440 PSI (30.3 BAR)
    Maximum Flow: 106 GPM (401 L/min)
    Maximum Head: 1,016 ft (310 m)
    Pump Type: 4-stage centrifugal

  • BB-4-21H Flow at Pressure

    At 150 PSI: 103 GPM (390 L/min)
    At 250 PSI: 94 GPM (356 L/min)
    At 350 PSI: 65 GPM (246 L/min)

  • BB-4-21H Configuration

    BB-4-21H: Vehicle mount, horizontal drive
    Engine: Honda GX630 twin-cylinder
    Power: 20.8 HP @ 3600 RPM
    Weight: 169 lbs

    Shop BB-4-21H 

BB-4-D902 (25 HP Kubota Diesel)

  • BB-4-D902 Performance

    Maximum Pressure: 395 PSI (27.2 BAR)
    Maximum Flow: 106 GPM (401 L/min)
    Maximum Head: 912 ft (278 m)
    Pump Type: 4-stage centrifugal

  • Kubota D902 Engine

    Engine: Kubota D902-E4B
    Type: 3-cylinder, liquid cooled diesel
    Power: 25 HP
    Features: Fuel injected, low maintenance

  • BB-4-D902 Configurations

    BB-4-D902V: Vehicle mount, vertical drive
    BB-4-D902H: Vehicle mount, horizontal drive
    FastWire: 14-pin connector standard
    Listed: USFS Type 6 Fire Apparatus specs

    Shop BB-4 Diesel 

Common Pump Specifications

All BB-4 models share these pump end specifications.

Pump End Specifications

  • Pump Construction

    Type: Detachable 4-stage centrifugal
    Body & Diffusers: Anodized corrosion-resistant aluminum
    Impellers: 3.67" diameter, anodized aluminum
    Pump Shaft: Stainless steel
    Max Allowable Pressure: 600 PSI (41.4 BAR)

  • Pump Connections

    Intake: 2" Male NPSH
    Discharge: 1-1/2" Male NPSH
    Priming Port: 1-1/2" Male NPSH
    Clamp: Hand-tight quick-release (no tools needed)
    Drive: Timing belt & pulley, 1.88:1 ratio

  • Seals & Bearings

    Bearings: Maintenance-free sealed ball bearing
    Pump Seal: Blister-resistant carbon seal face, silicon carbide seat
    Ratings: ISO 9 and NFPA 1906 Medium Pressure
    Special Feature: Pump separates completely from engine/speed increaser

Priming Options

  • Guzzler Hand Primer

    Type: Diaphragm, reliable & lightweight
    Lift: 12 ft (16 ft with foot valve)
    Volume: 0.44 quart per stroke
    Construction: Aluminum handle, composite body
    Shipped: Loose with hardware & 6 ft hose

  • Exhaust Primer

    Type: Venturi (mounted to exhaust primer muffler)
    Construction: Brass venturi, aluminum exhaust valve
    Operation: Remote mount push/pull cable
    Vacuum: Minimum 17 in-Hg

  • Electric Primer

    Type: 12 VDC piston vacuum pump
    Lift: 25 ft (7.6 m)
    Vacuum: 22 in-Hg
    Max Current: 105 amps
    Weight: 8.1 lbs with mounting plate

Applications

BB-4 pumps are designed for professional wildland firefighting operations where high pressure is essential to overcome terrain challenges.

  • Type 6 Brush Trucks & Slip-On Units

    The BB-4 has been the pump of choice for Type 6 brush trucks for over 40 years. Vehicle-mount configurations with FastWire connectors integrate seamlessly with WATERAX control panels.

  • Long Hose Lays

    High pressure output up to 440 PSI enables water delivery over extended distances. The 1,016 ft maximum head overcomes pressure losses from friction and elevation changes in rugged terrain.

  • Tandem & Parallel Pumping

    Strong enough to serve as a source pump for tandem and parallel pumping operations. Connect multiple BB-4 pumps in series for extreme pressure, or in parallel for increased flow.

  • High-Elevation Firefighting

    The 23 HP model is ideal for pumping at high altitudes where engine power loss is a concern. High pressure provides accuracy in flow trajectory for structure protection.

Documents & Resources

  • BB-4-21H Data Sheet

    Official WATERAX BB-4-21H Honda specifications, performance curves, and technical drawings.

    Download PDF →

  • BB-4-23V Data Sheet

    Official WATERAX BB-4-23V Briggs & Stratton specifications, performance curves, and technical drawings.

    Download PDF →

  • BB-4-D902 Data Sheet

    Official WATERAX BB-4-D902 Kubota diesel specifications and technical drawings.

    Download PDF →

  • Owner's Manual

    Complete operating instructions, maintenance procedures, parts breakdown, and safety guidelines for all BB-4 models.

    Download PDF →

Compare WATERAX Pumps

The BB-4 series delivers maximum pressure (440 PSI) for vehicle-mounted applications. For a backpackable high-pressure option, the MARK-3® delivers 380 PSI at 98 GPM in a 62 lb package. For higher flow at moderate pressure, the B2X™ mid-range pump delivers 180 PSI at 310 GPM.

View All WATERAX Pumps

Complete Your Setup

BB-4 pumps use 2" NPSH intake and 1-1/2" NPSH discharge connections, compatible with standard forestry hose and fittings.

  • Forestry Hose

    1-1/2" and 1" forestry lay flat hose. EPDM-lined for durability with NPSH forestry couplings.

    Shop Forestry Hose 

  • Fittings & Adapters

    NPSH couplings, wye valves, reducers, and adapters. 2" intake and 1-1/2" discharge compatible.

    Shop Fittings 

  • Control Panels

    WATERAX MCP, PMSCP, and WCP control panels for remote operation with FastWire connectivity.

    Shop Control Panels 

  • BB-4 Parts

    Genuine WATERAX replacement parts including pump ends, seals, impellers, and maintenance kits.

    Shop BB-4 Parts 

Shop BB-4 Pumps

Gasoline Models

  • BB-4-18V

    18 HP Briggs & Stratton Vanguard, vehicle mount. 440 PSI / 104 GPM. 153 lbs.

    View BB-4-18V 

  • BB-4-23V

    23 HP Briggs & Stratton Vanguard, vehicle mount. 440 PSI / 106 GPM. Ideal for high altitude. 154 lbs.

    View BB-4-23V 

  • BB-4-21H

    21 HP Honda GX630, vehicle mount horizontal drive. 440 PSI / 106 GPM. 169 lbs.

    View BB-4-21H 

  • BB-4-23PXTC Portable

    23 HP Briggs & Stratton with carry frame. Portable high-pressure option.

    View BB-4-23PXTC 

Diesel Models (Kubota D902)

  • BB-4-D902V

    25 HP Kubota diesel, vehicle mount vertical drive. 395 PSI / 106 GPM. FastWire 14-pin connector.

    View BB-4-D902V 

  • BB-4-D902H

    25 HP Kubota diesel, vehicle mount horizontal drive. Listed on USFS Type 6 Fire Apparatus specifications.

    View BB-4-D902H 

Shop Parts

Genuine WATERAX replacement parts ensure your pump delivers reliable performance season after season. From pump bodies and impellers to suction covers, mechanical seals, and shaft assemblies—we stock the components you need to maintain and service your pump.

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Need Help Selecting a Pump?

Whether you're building a Type 6 brush truck, specifying equipment for a forest agency, or need to match pump performance to your specific terrain and application, we can help you choose the right BB-4 configuration.

Contact Our Team