What size hydrovac do I need for utility potholing and daylighting?

For most utility potholing and daylighting, a small trailer or a mid-size truck is the right size. These jobs make many small, shallow holes and require frequent repositioning, so maneuverability, water capacity, and refill logistics matter more than large debris volume. A small trailer commonly carries around 2 to 6 cubic yards of debris and 200 to 800 gallons of water, which is plenty for a series of small holes, though you will dump and refill more often than with a larger truck.

How many cubic yards of debris capacity do I need?

Estimate the volume of spoil your job produces, then remember that wet, heavy slurry usually fills the tank on legal weight before it fills on volume. Because of that, your real dig-before-dump limit is whichever comes first, payload or volume. Light, dry material lets you use most of a tank's cubic-yard rating; wet clay and mud may max out the truck's weight at half to two-thirds of the rated volume. If the dump site is far away, a larger tank reduces trips; if it is close, a smaller tank can shuttle efficiently.

Does vacuum CFM or water PSI matter more?

They control different things, so it depends on the job. Vacuum power (CFM) determines how fast and how deep the unit lifts material up the hose, which matters most on deep excavations and long hose runs. Water pressure (PSI) determines how hard the jet cuts, which matters most in frozen ground, frost, and heavy clay. Soft, shallow work needs little of either; a deep hole in frozen clay needs strong CFM and high PSI together.

How deep and how far can a hydrovac dig?

Depth and horizontal reach are governed by boom reach plus vacuum strength. Boom reach commonly runs around 20 to 25 feet on mid-size trucks and up to roughly 25 to 30 feet on large trucks, with shorter reach on compact trailers. Deeper digs also demand stronger vacuum, because material has to travel farther up the hose, so deep work usually calls for a larger truck with more CFM and a positive-displacement blower rather than a small unit.

What is the difference in size between a hydrovac trailer and a hydrovac truck?

A hydrovac trailer is the compact tier: typically smaller debris and water tanks, lower CFM, and shorter boom reach, built to fit tight, weight-restricted, or hard-to-access sites. A hydrovac truck spans mid-size to large builds with bigger tanks, more airflow, and longer boom reach for higher-volume and deeper work. Trailers trade capacity for access; trucks trade access for capacity and production.

Do I need a bigger truck if the dump site or water source is far away?

Often yes. When the dump site is far, each dump cycle costs significant travel time, so a larger debris tank that lets you dig longer between hauls can pay off. The same logic applies to water: a distant fill point rewards a bigger water tank. When both the dump and water source are close, a smaller unit shuttles efficiently and a larger tank adds little. Balance this against site access, since a large truck that cannot reach or legally cross to the dig is the wrong choice regardless of tank size.

Rental guide

What Size Hydrovac or Vacuum Truck Do You Need?

The right size hydrovac or vacuum truck is the smallest unit that can finish your job without running out of water or debris space before your next dump or refill. In practice, sizing comes down to four specs (debris capacity in cubic yards, water capacity in gallons, vacuum power in CFM, and boom reach in feet), balanced against two things the specs cannot show you: how heavy your spoil is, and how far away your dump site and water source are. This guide breaks down small trailer versus mid truck versus large truck, gives typical spec ranges for each, and turns it into simple rules of thumb by job type and haul distance so you can request the right truck the first time.

Key takeaways

Size to whichever limit runs out first: water to cut, or debris space to hold spoil. The smallest unit that clears both between dumps and refills is usually the right one.
Debris tanks fill on weight before volume with wet, heavy slurry, so a large cubic-yard rating rarely means you get the full cubic yards; describe your soil so the rental company sizes for payload.
Small trailers (roughly 2 to 6 cu yd, 200 to 800 gal) win on tight access; large trucks (roughly 12 to 18-plus cu yd, 1,000-plus gal, 5,000-plus CFM) win on deep, high-volume, open sites; mid trucks cover most everyday work.
Match vacuum CFM, boom reach, and PSI to depth and soil: deep holes and long hose runs and frost need more of each; shallow, soft, close work needs little.
Let logistics break ties: far dump or far water pushes you up a size, tight access or weight limits pushes you down.

The four specs that actually decide size

Every hydrovac and vacuum truck is described by the same short list of numbers, and each one controls a different limit on how long you can dig before you have to stop.

Debris capacity (cubic yards) is how much spoil, slurry, or sludge the tank holds before you must haul it to a dump site. This sets your dump-cycle frequency. Water capacity (gallons) is how much cutting and rinse water you carry before you must refill, which sets your refill frequency on a hydrovac. Vacuum power (CFM, cubic feet per minute of airflow) determines how fast and how deep the unit can lift material up the hose; more CFM and stronger vacuum matter most on long hose runs and deep digs. Boom reach (feet) is how far and how deep the vacuum boom can work around obstacles and down into an excavation.

One more spec sits underneath a true hydrovac: the water system, rated in GPM at PSI (gallons per minute at pressure). Cutting water commonly runs around 8 to 12 GPM at pressures up to roughly 3,000 to 4,000 PSI. Higher pressure cuts frozen ground, frost, and hard clay faster; higher flow moves more soil per minute. If your soil is soft, GPM and PSI matter less; if it is frozen or heavy clay, they matter a lot. All of these figures are typical ranges that vary by manufacturer and configuration, not guarantees, so confirm the exact specs of any unit before you rent it.

Small trailer vs mid truck vs large truck (typical ranges)

Hydrovac and vacuum equipment roughly sorts into three tiers. Treat the numbers below as common industry ranges, not fixed values, because every build is different.

Small trailer or compact hydrovac: debris capacity commonly around 2 to 6 cubic yards, water around 200 to 800 gallons, airflow roughly 1,200 to 3,000 CFM, and a shorter or fixed boom reach. These fit tight urban lots, backyards, weight-restricted access, and jobs where maneuverability beats capacity. They shine on small potholes and quick daylighting, but you will dump and refill more often.

Mid-size truck (single or tandem axle): debris capacity commonly around 6 to 12 cubic yards, water around 500 to 1,300 gallons, airflow roughly 3,000 to 5,000 CFM, and boom reach around 20 to 25 feet. This is the versatile middle ground for most utility potholing, slot trenching, and mixed daily work.

Large truck (tandem or tri-axle): debris capacity commonly around 12 to 18-plus cubic yards, water around 1,000 to 1,800-plus gallons, airflow roughly 5,000 to 6,000-plus CFM, and boom reach around 25 to 30 feet. These are built for volume, depth, and long production runs on open sites where access is not a problem. They cost more to run and are the hardest to fit into tight or weight-limited locations.

The hidden constraint: weight beats volume

The most common sizing mistake is assuming a debris tank rated at, say, 12 cubic yards will hold 12 cubic yards of your material. It often will not, because you hit legal axle weight before the tank is visually full.

Wet slurry is heavy. Water-laden spoil, mud, and dense clay can weigh well over a ton per cubic yard, so a large debris tank frequently reaches the truck's legal payload limit at half or two-thirds of its volume. Your real dig-before-dump limit is whichever comes first: volume capacity or legal payload. Lighter, drier material lets you use more of the tank's volume; heavy wet slurry means you dump on weight.

The practical takeaway: if you are digging in wet or heavy soil, a bigger tank does not always mean proportionally fewer dumps, and a mid-size truck may cycle almost as efficiently as a large one while being far easier to place. When you request a truck, describe your soil conditions so the rental company can size for weight, not just for volume.

Size by job type

Different jobs load the four specs differently, so start from the work.

Daylighting and utility potholing (many small, shallow holes): prioritize maneuverability, water capacity, and refill logistics over raw debris volume. A small trailer or mid truck usually wins because you make lots of small holes and move often. See the hydrovac-truck and hydrovac-trailer type pages for options.

Slot trenching and larger excavations: you need both debris and water capacity, so a mid to large truck fits. Continuous digging burns water fast and fills the tank quickly.

Deep excavation, piling holes, and deep potholes: prioritize boom reach, strong vacuum (higher CFM, positive-displacement blower for deeper suction on long hose runs), and higher PSI to keep cutting at depth. A large truck is usually the right call.

Debris, sludge, catch basin, and sump cleanup: this is vacuum-truck work, not necessarily high-pressure hydrovac cutting. Size the vacuum truck to the volume of material and whether it is wet, dry, or a mix. For continuous liquid removal, a liquid-vacuum or liquid-ring unit is built for the task. Cold-weather digging adds its own requirement: higher PSI plus heated water and frost planning, covered in the winter rental guide.

Size by haul distance and site access

Two logistics questions often matter more than any single spec: how far is the dump site, and how far is the water source.

When the dump site is far, every dump cycle is expensive travel time, so a larger debris tank that lets you dig longer between hauls can pay off. When the dump is close, a smaller unit can shuttle efficiently and you gain nothing from carrying a huge tank. The same logic applies to water: a distant hydrant or fill point rewards a bigger water tank, while an on-site water source lets a smaller unit refill quickly and keep working.

Site access pulls the other way. Tight urban streets, narrow gates, indoor or confined spaces, weight-restricted bridges, and soft ground all favor a smaller trailer or compact truck that can actually reach the dig. A large truck that cannot get to the hole, or cannot legally cross the access route loaded, is the wrong truck no matter how good its specs are. The right answer is the balance: the smallest unit whose access clearances fit your site and whose tank sizes keep dump and fill trips reasonable for your haul distances.

Rules of thumb cheat sheet

Quick heuristics to get you close before you talk to a rental company:

Start with your two limits. Estimate roughly how much spoil the job produces (debris cu yd) and how much water it will take to cut it (gallons). Whichever runs out first sets your minimum size. Assume wet, heavy soil fills on weight, not volume, so do not over-trust a big tank's cubic-yard rating.

Match vacuum and boom to depth and distance. Shallow, close work is fine on modest CFM and a short boom. Deep holes and long hose runs need more CFM, stronger vacuum, and longer boom reach. Match PSI and GPM to soil hardness: soft ground needs little, frost and heavy clay need a lot.

Let logistics break ties. Far dump or far water pushes you up a size; tight access or weight limits pushes you down. When in doubt on a mixed day of small potholes, a mid-size truck is the safe default. When in doubt on tight urban access, a trailer or compact truck is safer than getting stuck. When in doubt on deep, high-volume, open-site work, go large.

How to get the right size on Vac4Rent

Vac4Rent is a marketplace to rent hydrovac trucks and trailers and the wider range of vacuum trucks and vac trailers, or to list yours for rent. You submit one free request describing your job (soil, depth, volume, site access, dump and water distance), and rental companies reply to you directly by email or phone with the units they have and their availability. There are no commissions and no booking fees, and Vac4Rent does not set or publish rental rates; you get real quotes directly from the rental companies.

As ballpark market context that varies widely by region, size, and whether an operator is included, operated hydrovac trucks commonly rent in the low thousands of dollars per day, while smaller trailer units often run less. Those are general industry figures, not Vac4Rent prices, and the only way to get an accurate number is to request quotes. For a fuller breakdown, see the cost guide.

Vac4Rent is operated by the Hydrovac News family of brands (Hydrovac News, founded in 1992, the Hydrovac Hotline provider network of roughly 1,790 trucks, and Hydrovac Magazine), bringing 34-plus years of industry experience. Describe your job in the request and let the rental companies help you match the truck to the work.

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