Water Supply Flow Priorities

“Instead of asking, ‘WHAT should we do …?’ questions must be asked, ‘WHY did we start doing WHAT we’re doing in the first place, and WHAT can we do to bring our cause to life considering all the technologies and market opportunities available today?’ ”1

The quote from Simon Sinek’s book, Start With The Why, highlights what should be the fundamental question for any fire department as we evaluate our tactics. Why do we do what we do? Is the manner in which we operate on the fireground consistent with our mission? Is it consistent with the service promise we made to the public?

Our fire department has made significant changes to engine operations over the past five years. It is one of an increasing number of departments that have switched from high-pressure nozzles [100-pound-per-square-inch (psi) automatic, 80- to 90-gallon-per-minute (gpm) based on flow tests] to low-pressure (smooth bore) nozzles. While we experienced immediate improvement in suppression capacity as a result of higher fire flows, we also noted unanticipated ripple effects such as difficulties with wye operations and limitations in our water supply operations.

During an apartment fire that required multiple handlines, the engineer of the 1,500-gpm-rated attack pumper operated near cavitation while flowing approximately 1,000 gpm. The second-due engine had forward laid 300 feet from a strong hydrant that we later estimated was capable of providing in excess of 2,000 gpm. This led to an internal review to determine why we were unable to flow the capacity of our 1,500-gpm pumpers.

Historically, we’ve been a forward-lay department, first with five-inch large-diameter hose (LDH) before switching to four-inch hose in 2008. Our service area is a mix of urban, suburban, and rural with both hydranted and nonhydranted areas. Hydrant spacing, volume, and pressure vary significantly across our service area where water supply infrastructure is managed by seven separate water districts. These variables complicated our efforts to adopt a single water supply operation.

Defining the Problem

The first step in evaluating our water supply limitations was to look at our supply hose. After discussing typical failure points of modern constructed supply hose with Captain (Ret.) Dennis LeGear2, we undertook the labor-intensive project of inspecting our entire supply hose inventory for signs of delamination. We found a significant percentage of our supply hose exhibiting evidence of delamination. After removing delaminated hose, we began flow testing our supply capacity. This flow testing revealed considerably less capacity than we previously anticipated.

The methodology for the testing consisted of a series of flow tests at our training center using a hydrant system with 65-psi normal operating pressure and a capacity of 2,000 gpm per hydrant. We used a combination of our newest pumpers (with REPTO drive pumps) as well as our older front-line engines (with split-shaft midship pumps). We also used a combination of forward-lay and reverse-lay configurations, both single supply line as well as multiple supply line operations. Fire flows were calculated with a calibrated pitot gauge on smooth bore master streams.

A forward lay of 600 to 1,200 feet limits our capacity to flow approximately 500 gpm. Operationally, this translates to an inability to support a third handline (170 gpm per 1¾-inch line; 275 gpm per 2½-inch line). If a third handline is required, a later arriving engine must pick up an additional hydrant. This additional hydrant would almost certainly be farther away from the scene and provide less volume than the initial hydrant.

However, by forward laying a second supply line (double header), we double our suppression capacity from 500 to 1,000 gpm. By reverse laying and pumping the hydrant, we could access 1,200 to 1,500 gpm. By reverse laying either a double header or doing a split lay, we exceeded the rated capacity of the pump by almost 500 gpm.

Chart 1: Forward and Reverse Lay Comparison at 600- to 1,200-Foot Distances

Policy Development

After quantifying our water supply limitations and identifying methods to significantly increase capacity, the next step was to create a policy or guideline. We faced several challenges in reworking our water supply policy—the first being our 235-square-mile response area and seven different water districts. Some areas are fed by modern 36-inch water mains, providing high volume and pressure (exceeding 150 psi in some zones). Other areas are served by old wooden water mains—low pressure and low volume. This poses a challenge to having one method of establishing a water supply that is effective across our response area.

The second challenge is the variety of staffing and resource concentration throughout the fire district. Our urban areas enjoy four-person staffing and stations in close proximity. Operations benefit from second- and third-due pumpers arriving shortly after the first-due. Our outlying stations have three-person engines and may have to wait 15 minutes for a second- or third-due pumper.

Third, we have a forward-lay culture. A common “rule of thumb” is “never drive by a hydrant en route to a confirmed working fire.” This practice is largely driven by a motivation to never run out of water. Admittedly, running out of water always looks bad. But, are strategies and tactics based on effective operations or public perception? This belief has been a barrier to both booster tank attacks as well as reverse-lay operations. Last, we have a mix of officers who want one standard and others who value the flexibility to make judgment calls.

In the end, we decided to provide “leaders’ intent.” We provided a series of priorities delineating what’s most important to achieve in terms of water supply. The priorities follow:

  1. Allow the first-due engine to initiate a booster tank attack as early as possible.
  2. Maximize company personnel on scene available for initial fire attack operations.
  3. Maximize available water from hydrants to operate at or above rated pumper capacity.
  4. Provide redundancy for mechanical breakdowns and failures or inadequacies of the water supply infrastructure.

The new water supply priorities stress as a primary tenet the power of “fast water” via the booster tank attack. The efficacy of the booster tank attack was supported by our improved suppression capacity with high flow rates as well as the initial test results from a UL Fire Attack Stream Study3. But most importantly, the booster tank attack is consistent with our primary goal of life safety. After our hose/nozzle change, we experienced fire control that was often achieved on booster tank water, and the hydrant was only needed for overhaul. We had several successes early on during which aggressive searches were possible because of early fire control. To this day, five years after the change, battalion chiefs and crews rave about how much fire they can put out with “our new smooth bores.” What we’ve experienced is our “bread-and-butter” residential fires can be controlled with 200 to 300 gallons of water. With booster tanks of 650 to 750 gallons, this provides a safety factor of approximately 3:1.

Based on the priorities above, we developed a water supply algorithm. This algorithm provides command and company officers with plans A through D. All of the plans start with the booster tank attack.

Fire operations begin with the first-due engine proceeding directly to the scene. This supports our first incident objective of life safety by getting the engine on scene as quickly as possible to assess needs for imminent rescue. It also allows for “fast water” through early hoseline deployment and appropriate line placement. By hitting the fire quickly with an appropriately placed 170 gpm, we begin to achieve fire control in support of our second incident objective of incident stabilization.

Plan A: First-Due Takes Its Own Hydrant

If the nearest hydrant is located within 100 feet, the apparatus operator shall hand stretch LDH and establish his own water supply. Based on our flow testing for four-inch LDH, we can expect full capacity of our 1,500-gpm pumper when spotting within 100 feet of the hydrant (average hydrant assumed to have 60-psi operating pressure and greater than 1,500-gpm capacity). Engine companies are encouraged to factor hydrant location into their spotting location and either stop short or pull past the fire building. Either way, this serves a dual objective of saving the front of the building for truck placement.

Plan B: Reverse Lay

If the first-due engine can’t spot within 100 feet of a hydrant, it defers water supply to the second-due engine and initiates a booster tank attack. The second-due engine should seek opportunities to reverse lay from the attack engine to a hydrant. By laying away from the attack engine, LDH is laid away from the fire scene and tends to leave better spotting for the first-due truck. On arrival at the scene, the second-due pumper’s officer and firefighter, fully dressed with self-contained breathing apparatus donned, exit the engine, obtain tools for their assignment, and are ready to work immediately. The apparatus operator of the second-due pumper, who typically drives in turnout bottoms only, proceeds away from the scene and establishes the water supply. If the fire flow requirements necessitate a relay operation, the apparatus operator can pump the hydrant. If a relay is not required, the apparatus operator simply takes the hydrant and is then able to don remaining personal protective equipment and proceed to the fire scene to join his crew. The advantages of reverse lay include the following:

  • More combat-ready personnel on scene for initial operations.
  • Less likely to block scene with LDH, and supply line is laid away from the scene.
  • Enhanced fire flow capacity with a pumper at the hydrant.
  • Pump redundancy with a pumper at the hydrant able to take over if the attack pumper has a mechanical issue.

Reverse lay is an excellent option when hydrant location and street grinding allow. However, this may not be a viable option on dead-end streets, cul de sacs, and many apartment complexes. As reverse lay is a newer tactic for our organization, we encouraged our officers to quickly look to plan C (forward lay dry with booster tank backup) if reverse lay does not appear easily implementable.

Plan C: Forward Lay Dry (Booster Tank Backup)

The booster tank backup is an excellent option for the vast majority of our residential structure fires. Battalion Chief Curt Isakson, of Escambia County, Florida, is an excellent resource for more information on this tactic.4 Booster tank backup is his department’s standard for water supply on residential fires and has facilitated multiple civilian rescues through early fire control via fast water tank attacks. This tactic entails the second-due engine proceeding to the scene and sharing its booster tank water with the first due to provide a total of 1,500 gallons of available water for initial operations. Plan C in our water supply entails the second-due engine forward laying dry from the hydrant and then sharing booster tank water. This gets a full staffed second-due engine to the scene relatively quickly, provides 1,500 gallons of water for initial attack, but also sets up the third-due engine to pump the hydrant if the initial 1,500 gallons prove insufficient.

Plan D: Forward Lay Wet

This is the typical water supply tactic used by departments with LDH. In some ways, it may be the safest or most comfortable, as the first- or second-due engine takes the last hydrant it passes on its way to the fire scene. The attack team knows that a permanent water supply is established early during operations. However, we have noted several downsides. First, it tends to be staffing-intensive in practice. A fully dressed and ready-to-work firefighter is dropped off at the hydrant remote from the fire scene and must remain there until supply hose connections have been made at the scene. The driver typically breaks the supply hose connection at the scene, often with the assistance of the officer. Thus, the forward-lay wet operation typically requires an entire engine company. The second-due engine is not available to assist with the first line during initial operations and is delayed in pulling a backup line. Additionally, our flow testing indicated this operation significantly reduces our ability to access the full water supply potential available in the hydrant system. It does provide enough water in most cases. We ultimately asked if this was the best plan A or if these successes constituted a normalization of deviance.

Strengths and Weaknesses

A department must examine its water supply tactics as a part of its overall suppression system. The best tactics will depend on water supply infrastructure, staffing, concentration, and reliability of response resources and your mission statement. We encourage you to take an honest and thorough look at the strengths and weaknesses within your system. Ultimately, you should strive to answer the WHY. Do you do what you do because it’s what you’ve always done? Or, are your water supply tactics based on your mission statement and service promise? Are your tactics based on what’s best for THEM?


1. Sinek, Simon. Start with Why: How Great Leaders Inspire Everyone to Take Action. Penguin Group, 2009.

2. LeGear, Dennis. Personal Interview, February 2-5, 2016.

3. The reference to initial test results from UL Fire Stream Study are based on videos and commentary by the testing agency posted to the UL FSRI Facebook page, which indicated one- and two-room fires were extinguished with less than 150 gallons of water. This was further corroborated by personal interviews with technical panel members.

4. Isakson, Curt. Personal and group Internet correspondence, 2016-2017.

PATRICK DUNNE is a 14-year veteran of the fire service and a lieutenant for Clackamas (OR) Fire District #1. Prior to his promotion, he served as an apparatus operator for six years.

SCOTT CARMONY is a 30-year veteran of the fire service. He is a battalion chief in Operations for Clackamas (OR) Fire District #1.

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