Should I use time or rate for fill/dump?

Either works. If time is > 0 it is used. If time is 0, the calculator estimates time from usable gallons divided by the rate (GPM).

Tanker Shuttle Calculator (Sustained GPM)

Q: How many tankers do I need to meet a target flow?

Enter your target GPM. The calculator computes sustained GPM per tanker and estimates the tanker count needed to meet or exceed it.

Field-friendly tanker/tender shuttle estimator for rural water supply. Enter tanker capacity, distance, average speed, fill/dump times (or rates), and a queue buffer. Outputs cycle time, sustained GPM, and estimated tanker count to meet a target flow.

Inputs

Number of tankers

Tanker capacity (gallons)

Usable water (%)

Conservative factor for partial fills, drafting loss, dump inefficiency.

Target flow (GPM) (optional)

Travel (Fill ↔ Dump)

One-way distance (miles)

Average speed (mph)

Travel time is computed as round trip: 2 × distance.

Fill + Dump (enter times OR rates)

If a time is > 0, it is used. If time is 0, the calculator uses the rate (GPM) to estimate time.

Fill time (minutes)

Fill rate (GPM) (optional)

Dump time (minutes)

Dump rate (GPM) (optional)

Queue / turnaround buffer (minutes per cycle)

Results

SUSTAINED FLOW (TOTAL)

—

Per tanker: — · Cycle time: —

Total water per hour

—

Tankers needed for target

—

Breakdown

Usable gallons per trip—

Travel time (round trip)—

Fill time—

Dump time—

Queue/buffer—

Cycle time—

Quick Links (use with this)

Fire Flow (Target GPM)PDP Calculator Friction Loss Hydrant Flow Hydrant Finder

Note

Training & preplan estimator. Real-world factors (traffic, site limitations, congestion) can change results. Use local SOP/SOG and officer judgment.

How this Tanker Shuttle Calculator works

Sustained GPM is estimated using a simple cycle model: Sustained GPM = Usable Gallons per Trip ÷ Cycle Time (minutes). Cycle time includes round-trip travel, fill, dump, and a conservative buffer.

Usable gallons applies a realistic percentage (default 90%).
If you don’t know exact times, set time to 0 and use a rate (GPM) to estimate time.
Use Target GPM to estimate how many tankers you need.

FAQ

Sustained GPM is the average continuous delivery rate based on cycle time (travel + fill + dump + buffer).

Either works. If time is > 0 it is used. If time is 0, time is estimated from usable gallons ÷ rate (GPM).

Enter a target GPM. The tool computes sustained GPM per tanker and estimates the tanker count needed to meet or exceed it.

Tanker Shuttle Calculator

Sustained GPM quick card (training/preplan). allfirefighter.com

Sustained Flow (Total)

—

Per tanker

—

Cycle time

—

Water per hour

—

Tankers needed (target)

—

Inputs (summary)

Target flow	—
Tankers × Capacity	— × —
Usable	—
Distance (one-way)	—
Avg speed	—
Fill / Dump / Buffer	— / — / —

Notes

Fill site: ____________ Dump site: ____________ Portable tanks: ____________ Traffic/queue: ____________