How much PSI is needed to jet a drain?
1,500 to 2,500 PSI for small interior lines, 3,000 to 4,000 for a 3 or 4-inch residential sewer, 4,000 to 8,000 for municipal and heavy commercial work. Flow in GPM matters just as much.
It depends on the line, and PSI alone is the wrong thing to shop for. The number that actually matters alongside pressure is flow, measured in gallons per minute, because volume is what carries debris out of the pipe. High pressure with low flow drills a neat hole and leaves the walls dirty.
A good technician also drops pressure deliberately on aging cast iron or cracked clay, which is a judgment call no spec sheet makes for you.
Pressure and Flow by Line Size
| Line | Typical Pressure | Typical Flow |
|---|---|---|
| 1.5–2 in. sink, lavatory, laundry | 1,500–2,500 PSI | 4–8 GPM |
| 2–3 in. kitchen and branch lines | 2,000–3,000 PSI | 8–12 GPM |
| 3–4 in. residential sewer lateral | 3,000–4,000 PSI | 10–18 GPM |
| 4–6 in. commercial building main | 3,500–4,000 PSI | 18 GPM and up |
| 6 in. and larger municipal | 4,000–8,000+ PSI | 40 GPM and up |
Treat these as starting points, not specifications. Nozzle selection shifts the effective result more than a few hundred PSI does.
Why GPM Is the Number to Ask About
Pressure cuts; flow carries. A machine at 4,000 PSI and 4 GPM will cut a clean hole through a grease plug and leave the pipe wall coated, because there is not enough water volume to move the material 50 feet back to the cleanout. A machine at 3,000 PSI and 14 GPM cuts slightly less aggressively and actually evacuates the line.
This is why PSI-only advertising is a soft tell. "Up to 4,000 PSI" with no flow figure usually means a small pump. Ask for both numbers.
When Less Pressure Is the Right Answer
Deliberately reducing pressure is a sign of competence, not weakness. On cast iron with a channeled invert, dropping to 2,000 to 2,500 PSI with high flow and a flushing nozzle cleans the scale without stressing what is left of the wall. On clay with offset joints, lower pressure avoids washing out the bedding soil behind the gap. On Orangeburg, the right pressure is usually none at all.
The technician reads this off the camera footage, which is the whole reason the camera goes in first.
Nozzles Do Half the Work
Same pump, four different outcomes depending on the head. A penetrating nozzle with a forward jet opens a solid plug. A flushing nozzle with all-rear jets maximises debris transport on grease. A chain or cutter head scrapes roots and scale off the wall mechanically. A rotating head gives even wall coverage in scaled cast iron.
The pumps we run, the nozzle set on the truck, and the pressure ranges we use by pipe material are listed on our hydro jetting equipment and process page.
Ask what pressure your pipe can take: (562) 316-3598Want the line looked at first?
We camera the pipe before we quote, then give a flat price. If cabling is the right call for your line, we will tell you that instead.
Call (562) 316-3598