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Built to Outlast.
Engineered to Outperform.
If you’ve been around a sewer jetter, you’ve heard a lot of talk about PSI. It’s usually the first number on the technical sheet. The problem is that PSI only tells part of the story. More PSI doesn’t automatically mean better cleaning. The best sewer jetters balance pressure (PSI), flow (GPM), and nozzle choice to deal with the job at hand. That’s why two experienced plumbers may approach the same line differently and both get great results.
If you’re looking for a chart that tells you exactly what PSI and GPM to run on every type sewer line, you’re not likely to find it. Each line is different and you start to hear a lot of “It depends” stories. Grease acts differently than roots. A 4-inch residential sewer is different from a 15-inch municipal sewer. Professional crews make adjustments all day long based on what they find once they’re in the line. Still, there are some good starting points.
The easiest way to think about jetting is this:
PSI (Pressure) – It cuts and tears apart roots, grease, and blockages.
GPM (Flow) – It carries debris out of the line and cleans the pipe wall.
Think about root blockage. Pressure may help cut it apart, but those roots still have to be flushed down the line. The same thing happens with grease. You can break it loose, but if you don’t have enough water to move it, you’re not done yet. That’s why experienced operators spend less equal time considering PSI and whether they have enough water to finish the job.
It’s not an exact science, but there are guidelines. Just not rules. Pipe condition, nozzle choice, hose size, and years of experience all come into play.
| Job Type | Typical PSI Range | Typical GPM Range |
|---|---|---|
| Residential Drains | 2,000–4,000 | 8–18 |
| Commercial Maintenance | 3,000–4,000 | 12–18 |
| Grease Removal | 2,500–4,000 | 18+ |
| Root Cutting | 3,000–4,000 | 12–18 |
| Municipal Sewer Cleaning | 2,000–3,500 | 18+ |
| Large Sewer Main Cleaning | 1,500–3,000 | 18+ |
One thing you see is that the largest cleaning jobs rely on more flow rather than extreme pressure. The size of the pipe changes what matters most.
| Pipe Size | What Usually Matters Most |
|---|---|
| 2″–4″ | Moderate pressure does most of the work |
| 6″–12″ | Balance of pressure and flow |
| 12″+ | Flow becomes very important |
In smaller lines, pressure can be more effective. As pipes get larger, moving debris becomes the real challenge. That’s one reason municipal crews have to focus on flow. Once you break material loose, you still have to get it moving down a long, wide line.
Most sewer cleaning work doesn’t need extreme pressure. In fact, many operators find they get better results by matching the right nozzle and flow to the job instead of simply turning up the pressure. Excessive pressure has some harsh downsides, too. It will accelerate wear on equipment faster, forcing more downtime and maintenance for repairs.
The real goal is to get the line clean, quickly and safely.
The nozzle you choose will completely change how a jetter performs. Most professionals will tell you that the wrong nozzle can make a good jetter perform poorly.
| Job Type | Common Nozzle Choice |
|---|---|
| General Cleaning | Penetrator |
| Grease Removal | Flusher |
| Root Cutting | Root Cutter |
| Heavy Debris | Cleaning Nozzle |
| Preventative Maintenance | General Cleaning Nozzle |
Pressure, flow, and nozzle choice all have to work together. Changing any one of them usually changes the way the entire setup behaves in the line.
If you’re trying to narrow down a machine, start with the type of work your crew is doing most often.
| If You Mostly Run… | Focus On |
|---|---|
| Residential Service Calls | Balanced PSI and GPM |
| Commercial Maintenance | More Flow and Longer Run Time |
| Restaurant Grease Lines | More Flow |
| Root Cutting | Pressure Plus the Right Nozzle |
| Municipal Sewer Cleaning | Higher Flow Capacity |
| Large-Diameter Pipe Cleaning | Flow Over Extreme Pressure |
Most situations don’t need extreme pressure. What they do need is a machine that cleans the line efficiently, holds up to the abuse of the crews, and keeps earning money instead of being taken offline for repairs.
If you’re comparing jetters, don’t just look at PSI. Look at the balance of pressure, flow, hose size, nozzle options, and match that to the kind of work you do every day.
Still not sure what PSI and GPM combination makes sense for your work? Talk with a Harben distributor or call us directly about the types of jobs you run most often. They can help you narrow down the right machine, hose, and nozzle setup. You can also learn more from our article: Matching Pressure, Flow, and Nozzle to the Job