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Glossary

GPM (Gallons per Minute)

What is GPM (Gallons per Minute)?

GPM (gallons per minute) measures the water flow of a hydrovac's pressure system; combined with PSI it determines how effectively the wand cuts soil during hydro excavation.

GPM describes how many gallons of water the pump delivers each minute to the wand. Together with PSI (pressure), GPM governs the cutting power of the water jet: higher flow moves more material, while pressure concentrates the cutting force.

The right GPM and PSI balance depends on soil type; hard or frozen ground may need more pressure, while loose soil needs less. Water capacity in gallons then limits runtime before refilling. On Vac4Rent, water systems are listed as a GPM at PSI range; request equipment matched to your soil.

Guides that cover GPM (Gallons per Minute)

Related terms

PSI (Pounds per Square Inch)Water TableHydro ExcavationDig Tube / Wand

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GPM (Gallons per Minute): common questions

What is GPM (Gallons per Minute)?+

GPM (gallons per minute) measures the water flow of a hydrovac's pressure system; combined with PSI it determines how effectively the wand cuts soil during hydro excavation.

Does a higher GPM always mean faster hydro excavation?+

Not always. More flow can move soil faster, but every extra gallon ends up in the debris body as slurry, so the tank fills sooner and the water supply runs out sooner. In loose soil, lower flow often digs efficiently while producing less slurry to haul. Operators balance GPM and PSI for the soil type rather than running maximum flow all day.

How does GPM affect how long a hydrovac can dig before refilling?+

Run time is roughly the usable water tank capacity divided by the flow rate being used, and wands are not spraying every minute, so real run time is often longer. A higher GPM setting empties the tank faster, which means more refill stops. On sites without a nearby hydrant or water source, crews often add a water truck. Ask the rental company about tank capacity and approved refill points.

Is GPM rated differently for sewer jetting and hydro excavation?+

Yes. On a combo truck, the jetter pump's flow scours the pipe and carries debris back toward the manhole where the vacuum hose picks it up, so jetting systems are rated for that purpose. A hydrovac's excavation pump is rated for cutting soil through a wand. The two are separate specs, so when renting, ask for the flow and pressure ratings of the specific system you plan to use.