Once a particular method or requirement for fire suppression system drainage has been identified, the drainage system and components need to be incorporated into the overall building design and construction.

Various applications of drainage in the design, operation and maintenance of fire protection systems were considered in the first part of this article. These applications generally respond to the following fire protection design methods or requirements:
  • Freeze protection
  • Removal/control of waste water from fire systems
  • System testing
  • Containment/control of fire spread related to hazardous materials
  • Minimize water damage to sensitive occupancies

Once a particular method or requirement for fire suppression system drainage has been identified, then the real work begins. Now the drainage system and components need to be incorporated into the overall building design and construction. This requires coordination with mechanical, electrical and plumbing services in the building. The aesthetic and architectural objectives of the building must also be considered.

There are ways of possibly reducing or eliminating drainage requirements where the provision and coordination of required drainage or containment prove to be too arduous. Examples are listed here.

Fire Suppression Alternatives

Alternative suppression systems such as gaseous clean agent fire suppression, foam systems (especially high-expansion foam), dry chemical suppression, or water mist fire suppression should be considered. These alternative systems are applicable where fire suppression is provided for buildings or spaces involving the storage, use, or handling of flammable/combustible liquids, toxics, corrosives, or other hazardous materials that require drainage and/or containment, and there is a desire to minimize the capacity and complexity of the containment/drainage system. These types of suppression systems may reduce or even eliminate drainage or remote containment/retention systems, thereby reducing cost, as well as design and construction complexity.

Pressure Relief Valve Alternatives

Consider replacing pressure relief valves with pressure-reducing or pressure-restricting valves that do not need to "relieve water" to drain but simply reduce pressure via an internal restricting orifice or pilot-operated valve arrangement.

This is most applicable in a design where a fire pump is being used to satisfy the fire protection system demand pressures and flows. Though such a design should be avoided, where possible, it may be necessary to provide a pump that will exceed the rated working pressure of the downstream system components. This would generally occur at pump churn (zero flow) or where the pump is operating along the upper end of the curve. Where excessive pressures are inevitable, a means of controlling or relieving this pressure in conjunction with any required drainage will need to be considered.

Cost-Effective Alternatives

At least one manufacturer has come up with a device that essentially incorporates the necessary requirements to flow test the sprinkler alarm switch for a specific zone without having to discharge water to drain. It incorporates a small pump that takes water from the main downstream of the flow switch then discharges the water back into the main upstream of the flow switch thereby circulating water past the flow switch and allowing it to operate. It can be operated automatically and remotely. Long term, this can save time, water, and ultimately money.

The vendor of this device indicates that it can save as much as 400 gallons per flow switch per year. It is also touted to significantly reduce testing time. It could take a maintenance person 15 to 20 minutes per flow switch (possibly more) to go to each location, get on a ladder, operate the valve, radio to another person monitoring the fire alarm panel, shut the valve, gather up the tools and then move on to the next location. The savings would be as follows:

Description: 1 flow switch w/ testing device
Water Savings: Up to 400 gallons
Time Savings: 15 - 20 minutes

For a 12-story building with 2 zones (2 flow switches) per floor, and a flow switch at the main incoming water service, the savings could be as follows:

Description: 25 flow switches w/ testing devices
Water Savings: Up to 10,000 gallons
Time Savings: 6 to 8 hours, 2 people

If done automatically and remotely (i.e. adjacent to the fire alarm panel), one person could test all of the flow switches simultaneously in the time it would take to test just one switch in the conventional manner. With today's consciousness toward environment, conservation and "green design," the water savings is considerable. Multiply this by the number of times the switches are tested each year and the savings could be even more significant.

Flow Meter Alternatives

Flow meters can be employed in lieu of the fire pump test connection hose valve header. The flow meter would be installed on a bypass pipe around the pump and can be used to test the pump flow and pressure at various points along its pump curve. The water is flowed around the pump in a closed loop, therefore eliminating the traditional full flow pump test where water is flowed through a number of hoses with flows measured by placing a pitot gauge at the end of each of the flowing hoses. Again, this can save time, money and water. Flowing a 2000 gpm fire pump up to 150% of its capacity as required by NFPA 20, during a 20- to 30-minute test, could expend in the neighborhood of 60,000 gallons of water.


In Parts 1 and 2 of this article, the impact of drainage concerns and requirements relative to fire protection system design and engineering have been explored. As seen here, careful consideration of alternative fire protection methods or approaches may provide ways of reducing or possibly eliminating altogether the need for drainage. The following checklist is provided as a tool to aid the designer or engineer in navigating the numerous issues and concerns related to fire protection system drainage.

Fire Protection System Drainage Design Checklist

  • Review applicable codes and standards regarding drainage requirements various types of fire protection systems applied in the project, considering the following:
    • Wet-pipe vs. Dry-pipe Sprinkler/Standpipe Systems
    • Pressure Regulating Hose Valves Used on Standpipe Systems
    • Fire Department Connections
    • Foam/Water Fire Suppression Systems
    • Pressure Relief Valves
    • Fire Pumps and Associated Components
    • Backflow Preventer

  • Types of Suppression System Test and Drain Connections
    • Main Drain at System Riser Assembly(s)
    • Alarm Test Connections (Inspector's Test Connection)
    • Auxiliary Drains (Low Points)
    • Automatic Ball Drips at Fire Department or Pump Test Connections

  • What size piping is required for the test or drain connections? What is the capacity and what flow can be expected from these drain connections?

  • Test and Drain Connection Discharge Outlets
    • Do the test connections need to be located at the remote end of the system or systems?
    • Are test/drain locations located such that there is a path for routing the drain discharge to the outside of the building?
    • For test/drain connections below grade, how will the discharge be handled?
    • If the below-grade drain discharge cannot be piped to the outside, can the drainage be taken via an indirect waste connection to the sanitary or storm sewer systems?
      • Are properly sized drains or sumps available to accommodate the discharge?
      • Can this drain connection be located in an area (janitor's closet, mech. room, etc) where a system back up or some splashing is acceptable without causing damage?
      • How will any trapped water which is not able to be drained by gravity be removed from the system?

  • Where is a safe and appropriate place to terminate the drain discharge outside?
    • Will it cause a safety hazard buildup of ice in the winter?
    • Will it damage landscape; are splash blocks or some other type of hardscaping material required?

  • Drainage/Containment Requirements
    • In relation to drainage and containment, can a hazardous material discharge and subsequent sprinkler discharge be accommodated within the room by curbs, recessed floor, ramps, trenches, etc.?
    • Does this discharge need to be drained away from the room or building to a properly designed retention/impounding area or holding tank?
    • Where can a required holding tank be located (aboveground, underground, inside or outside the building)?
    • How will the hazardous material laden sprinkler discharge be ultimately removed from the holding tank or containment/retention area and properly disposed of?

  • Is drainage required to divert sprinkler/standpipe discharge in order to provide greater protection and/or safety for a special occupancy?
    • Computer/Data Processing room per NFPA 75
    • Elevator shaft per ANSI/ASME A17.1
    • Electrical Equipment Room

  • Coordination
    • Do the drain systems and piping need to be concealed with the building construction? Can they be concealed within the building construction?
    • Can the drain connections be located so that the test or drain valve are easily accessible? Is the discharge point readily accessible and visible?
    • For the drain terminations on the exterior of the building, are there any architectural/aesthetic concerns to be addressed? Special pipe materials required? Specific location of drain terminations on wall of building?

  • Consider ways of minimizing or eliminating the amount fire protection system discharge which must be accommodated by drains.
    • Use of alternative fire suppression methods
      • Clean Agent Gaseous Suppression?
      • Dry Chemical Suppression?
      • Foam (Especially High Expansion)?
      • Water Mist?
      • Other?

    • Investigate listed and approved containers of smaller capacities which will not require containment of sprinkler water discharge.
    • Can pressure regulating or restricting valves be used in lieu of relief valves?
    • Utilize special closed loop flow switch testing devices.
    • Use listed and approved flow meters in lieu of traditional full flow pump test connections for the testing of fire pumps.
    • Can low points be eliminated thereby reducing the number of drain points?