Water, Water Everywhere: How Much Can We Move?

For as long as people have been making fire, they have been using water to put it out. From bucket brigades to horsedrawn steamers and now modern computer-controlled electric pumpers, water has been moved from a source to the fire.

It does not matter whether it is a wildland or a structural fire—the concept is the same. Our job as firefighters is to efficiently transport the water from a source to the fire and apply that water. Modern pumpers can deliver 2,000 gallons per minute (gpm) with ease. Do we have a source that can deliver that much water to the fire scene? I intend to take this question and make it a point of conversation and training for fire departments.

Let’s take a brief look at what has changed with fires. Legacy construction used wood, wool, or fiberglass insulation; copper pipes; and furniture made from natural materials. The times from ignition to flashover were 12 to 20 minutes. Current construction practices use more synthetic materials for insulation, PVC pipes, and petroleum-based foams for furniture that reach flashover in a few minutes. Delivering the water quickly and efficiently is more important than ever.

Apparatus

The apparatus we use come in all shapes and sizes. There are custom-built apparatus where we can specify everything or a stock chassis and basic pumping apparatus. The function remains the same though: put water on the fire. It is how much water we hope to move that can be specified on different apparatus. Class A pumps range from 1,000 to 2,500 gpm. Which apparatus gets ordered is determined by the needs of the buying entity. We know that industries may need a high volume of water while residential areas can employ the standard 1,500-gpm pump. Communities that have limited water supply locations, either hydrants or cisterns, may require long hoselays. Communities with tight streets or older water supply infrastructure also may require apparatus to carry larger amounts of supply hose. These requirements can adversely affect the amount of tank water that can be transported by the apparatus. The reliance of moving water to supplement the onboard water can be critical to a successful outcome.

Large-Diameter Hose (Ldh)

Typical supply line diameters are 4 inches and 5 inches. Anything more than that becomes unmanageable for firefighting personnel. A 6-inch empty hose requires numerous personnel to handle and becomes almost impossibleto move when filled with water. Departments that use 5-inch supply hose are doing better, as it can be moved to the side of the road but requires multiple firefighters to move once charged with water. The bonus is that the 5-inch can supply most apparatus to capacity with minimal friction loss. We are then limited by the water source. Many hydrant systems may not have the capacity to supply the 2,000 gpm 5-inch LDH can deliver.

Now, we get to the workhorse of the industry: the 4-inch supply hose. Because of its increased capacity over the old standard 3-inch hose, ease of use with the rubber jacket, lighter weight both dry and wet, and the amount of space required to pack more than 1,000 feet on apparatus, many departments are now using 4-inch as a standard practice. The 4-inch can supply 1,000 gpm with ease. Hoselays typically go from 100 feet to more than 1,0 feet. All in all, 4-inch seems to be ideal for supplying the apparatus we are using in communities all around the country as long as 1,000 gpm will put out your fire.

Water Delivery

Municipal water systems can provide a variety of volumes depending on the source of the water, the elevation relative to the source, and the age of the infrastructure providing the water. There will typically be large tanks on higher elevations to hold the water in reserve andprovide the head pressure for the delivery system. A treatment plant will have pumps that are set to maintain minimum and maximum pressures in the system at the plant that relate to the height of the water in the tanks. When necessary, the plant can increase the volume in the system by manually adding more pumping capacity. Thus, everything with water delivery is related, depending on the needs of the incident. That includes how we move the water to the scene. As a side note, supplying an attack apparatus from a remote location is almost identical to this system on a much smaller scale.

Many fire incidents we respond to do not require the large volumes of water that can be delivered. Single room-and- contents fires may only use two or three handlines delivering 180 gpm each—a maximum of 540 gpm for three 1 3/4-inch hoselines. A 4-inch hose supplying 1,000 gpm has made it very easy to become complacent with laying the single supply line from the source.

Most apparatus bought today are being supplied with 1,250-gpm pumps at a minimum. Also, 1,500- and 2,000- gpm pumps are becoming common. An apparatus committee will promote the apparatus to finance committees by citing the increased pumping capacity. The higher pumping capacity sounds like a great option, but the reality is we need to also consider that we can only put out as much water as we can put into the apparatus. If the supply is a single 4-inch hose, then we are now limiting the apparatus capacity to 1,000 gpm. The simple fix is adding a second supply line to the equation. This is the basis of dressing a hydrant fully with a hydrant assist valve and gated valves off both ears. Now we can maximize the amount of water taken into our apparatus from whatever the hydrant is able to supply. When the hydrant can supply more than 1,000 gpm, we can lay a second line to the attack pumper. This may also be the case if the supply pumper is drafting from a source and supplying an attack pump at the fire scene.

1 Municipal water systems can provide a variety of volumes depending on the source of the water, the elevation relative to the source, and the age of the infrastructure providing the water. (Photo by Jerry Bergquist/ShutterStock.com.)

How many times do we lay into a fire with more than one 4-inch supply line? From my experience, the answer is pretty much never. The usual answer is: If we need more water, we will have another pump lay in from another hydrant or source. We now have two 1,250-gpm or greater pumps supplying 1,000 gpm each. This is where the driver/engineer must do his own size-up when approaching the fire scene. Nothing showing can mean the 4-inch is going to be OK, but with smoke showing, perhaps dropping two 4-inch lines from the source when proceeding to the scene is a better idea. Then the hydrant pumper can maximize the water available with minimal friction loss.

The fire service, in general, becomes accustomed to doing the same thing over and over again. It really doesn’t affect those departments that use 5-inch as a regular supply line. Departments that lay 4-inch for every supply line are limiting themselves to a 1,000-gpm pumper when only one is laid out. Why have we fallen into this trap? Mostly because it works forus most of the time. A fire that requires three 1 3/4-inch lines and a 2 1/2-inch line, approximately 790 gpm, is still under the capacity of a 4-inch line.

Why Is It Important?

What scenario may require more than 1,000 gpm? Examples that come to mind are the McMansions that are being built everywhere. They may have long driveways, no rear access for apparatus, or be built in rural areas with no hydrants.

A fire could require both handlines and a ladder pipe to control the fire. Stories of these fires can be found all over the Internet. Multiple 4-inch lines will need to flow to the scene to handle the demand. These houses could be around for decades. History has shown that not all structures are maintained properly, with some becoming prone to fires.

Apparatus specified with 3-inch or LDH discharges can pump the single 4-inch, but to handle a second LDH line, the apparatus will need a second larger discharge or use two of the 2 1/2-inch discharges wyed together for another 4-inch line. A single 2 1/2-inch discharge will only supply approximately 850 gpm. If we adapt the single discharge to 4-inch, we again limit the amount of water we can deliver. When we are training, we are only limited by our imagination. Trydifferent configurations to maximize the possibilities of scenarios we might encounter.

Most communities have special situations or larger structures that could require large quantities of water. Seattle, Washington, had a fire in March 2023 at a boat storage facility. High volumes of water were needed to suppress the fire. Multiple relays were used from hydrants blocks away (“Seattle Fire Boat Storage Fire”, Fire Engineering, November 2023). I realize that salt water is not optimum for fire suppression, but the fireboat on scene sometimes supplies land- based units. In the article, it is reported that there was water on three sides of the storage facility. Perhaps one of the pumpers could have drafted off the pier, maximizing water delivery with the minimum number of apparatus. I have found that larger cities are so used to operating from hydrant water that they don’t consider drafting as an option.

Apparatus manufacturers will continue to offer bigger and better apparatus. How we use these apparatus is up to us. Let’s not turn a brand new 1,500-gpm pump into our old 1,000- gpm model it replaces by limiting our greatest resource—the water it is designed to move. Through training and thinking outside the box, we can keep up with technology as it evolves.

No matter how big the fire is, the most abundant suppression agent is still water. How departments use the available water can vary almost as much as the types of incidents we are called to handle. What we don’t want to do is make moving water harder than it has to be. Hydrants typically have three ports on them. Using only one of them limits the available water supply. When we draft from a source, the limiting factor is still what can be pushed into the pump. By adding a second avenue for the water to enter the pump, we reduce the work that has to be done to allow the pump to move that water to where we can use it. Once we overcome availability issues, we must make it easier to put the water on the fire. More than one supply line to an attack apparatus can reduce friction loss, reduce the number of apparatus clogging up the scene, and maximize the amount of water that can be used by firefighters. The only downsides I have found with laying multiple supply lines is with scene access and the availability of the hose on the apparatus. Preplanning, training, and communication can overcome these deficiencies.

related content

• Rural Water Movement Operations
• Water Delivery: The Year in Review
• Big Fire—Big Water for Rural Communities
• Moving Water: Supply Lines
• Where’s the Water?

DON POOLE is a 40-year veteran with the Rockport (MA) Fire Department. He has been teaching at the department’s fire academy for 26 years. He has a bachelor’s degree in fire science and administration.

The post Water, Water Everywhere: How Much Can We Move? appeared first on Fire Apparatus: Fire trucks, fire engines, emergency vehicles, and firefighting equipment.