How to Choose the Right Combination Sewer Truck

A combination sewer truck, often called a "combo truck" or "combo unit," is the workhorse of municipal sewer maintenance. It combines two essential functions into a single vehicle: high-pressure water jetting for cleaning pipes and a powerful vacuum system for removing debris. Instead of dispatching two separate trucks (a jetter and a vacuum truck), a combo unit handles both jobs in one trip, saving time, labor, and fuel.

These trucks are used daily by municipalities, utilities, and contractors for routine sewer line maintenance, emergency blockage clearing, catch basin cleaning, and even light hydro excavation. Choosing the right one is a decision you'll live with for 10–15 years, so it pays to evaluate your options carefully.

The most fundamental decision in specifying a combination truck is how to split your tank capacity between fresh water (for jetting) and debris (for vacuum collection). Common configurations range from a 50/50 split up to 70/30 water-to-debris ratios.

Key considerations:

• 50/50 split: Best for balanced operations where you're doing equal amounts of cleaning and material removal. Ideal for catch basin cleaning where you need substantial debris capacity.
• 60/40 or 70/30 water-heavy: Better for long mainline cleaning runs where you need maximum jetting capacity. You'll make fewer water refill stops, which means more uptime per shift.
• Tank material: Stainless steel tanks resist corrosion from sewer gases and abrasive materials. They cost more upfront but dramatically extend the life of the truck. Mild steel tanks are cheaper but will corrode faster in sewer environments.

Most municipalities running mainline cleaning programs will benefit from a 60/40 split. If your operation skews heavily toward catch basin work, consider 50/50.

The water pump is the heart of the jetting system. Pump performance is measured in gallons per minute (GPM) and pounds per square inch (PSI). Higher GPM means more water volume for pushing debris downstream, while higher PSI delivers more cutting force for roots and hardened deposits.

Typical pump ranges:

• Standard duty (60–80 GPM, 2,000–2,500 PSI): Adequate for routine maintenance in lines up to 18 inches
• Heavy duty (80–120 GPM, 2,500–3,000 PSI): Required for larger mains, heavy grease, and root intrusion
• High performance (100+ GPM, 3,000+ PSI): For the most demanding operations including large trunk sewers, industrial applications, and aggressive cleaning schedules

When comparing pumps, look at continuous duty ratings, not peak numbers. A pump rated at 80 GPM continuous will outperform one rated at 100 GPM peak if the peak-rated pump can only sustain that output in short bursts.

The vacuum system determines how effectively you can remove debris from the pipe and transfer it to the debris tank. There are two main types:

• Positive displacement (PD) blower: Delivers consistent vacuum regardless of conditions. Better for wet, heavy materials. More expensive but more versatile. Required if you'll also use the truck for light hydro excavation.
• Fan-type vacuum: Less expensive and simpler to maintain. Works well for dry or semi-dry debris but loses efficiency with wet, heavy material. Typically adequate for routine sewer maintenance.

If your operation includes any hydro excavation work, even occasionally, invest in a PD blower. The versatility will pay for itself.

The boom (the extendable arm that positions the vacuum hose) needs to reach from the truck to the manhole or catch basin. Standard boom reach ranges from 8 to 14 feet, with 10 feet being the most common for municipal work.

Hose reel capacity matters too. You need enough jetting hose to reach the full length of the pipe segments you'll be cleaning. Most municipalities specify 600–1,000 feet of jetting hose. Longer hose capacity means you can clean longer runs from a single manhole access point, reducing setup time.

Look for hydraulic-powered hose reels with automatic level-wind for consistent, tangle-free operation. Manual rewind reels save money upfront but cost you time on every job.

Water recycling systems filter the vacuumed water and return it to the fresh water tank for reuse. This can reduce water consumption by 50% or more, which means:

• Fewer trips to refill water, meaning more productive time on the job
• Lower water costs, significant for municipalities paying by the gallon
• Ability to work in areas without hydrant access
• Environmental compliance in water-restricted areas

Water recycling adds cost and complexity, but for high-volume mainline cleaning programs, the productivity gains are substantial. Calculate your daily water usage and refill downtime to determine ROI for your specific operation.

The chassis is the foundation of your combination truck. Key decisions include:

• GVWR class: Most combo trucks are built on Class 7 (26,001–33,000 lbs) or Class 8 (33,001+ lbs) chassis. Larger chassis accommodate bigger tanks and more powerful systems but may require a CDL to operate.
• Engine: Match engine horsepower to the demands of your pump and vacuum systems. Under-powered engines lead to poor performance and premature wear.
• Cab configuration: Single cab is standard. Extended or crew cabs add space for operators but increase overall length, which can be a problem on narrow streets.
• Transmission: Automatic is now standard for most municipal applications. Manual transmission is less common but preferred by some operators for specific terrain.

Work with your dealer to match the chassis to the body spec. The chassis and body need to be engineered as a system, not cobbled together from separate specifications.

A new combination sewer truck represents a significant investment, typically $350,000 to $600,000+ depending on configuration. But purchase price is only one piece of the total cost equation.

Factor in these ongoing costs:

• Maintenance: Pump rebuilds, hose replacement, vacuum system service, hydraulic maintenance. Budget $15,000–$25,000 annually.
• Consumables: Nozzles, hose couplings, filters, hydraulic fluid. Budget $5,000–$10,000 annually.
• Downtime cost: What does it cost your operation when a truck is down? Better-built trucks with readily available parts minimize this.
• Resale value: Premium brands retain value better. A $500,000 truck that's worth $150,000 at 10 years may be cheaper to own than a $400,000 truck worth $50,000 at 10 years.

Consider reconditioning as an alternative to buying new. A professionally reconditioned combination truck can deliver 80% of new-truck performance at 40–60% of the cost.