Can hydro jetting damage PVC pipes?

Hydro jetting cleans a drain or sewer line with a stream of water from a hose and nozzle fed by a high-pressure pump. Jets on the nozzle point backward, so the water pulls the hose up the line while it scours grease, scale, sludge and roots off the pipe wall and washes them downstream. Our page on what hydro jetting is covers the basics.

TEPPFA, the European plastic pipe and fittings association, had the Danish Technological Institute test PVC-U, polypropylene and polyethylene sewer pipe, in solid and structured wall types. Each one took the 120 bar test above with no damage. Its bulletin goes further and says that, in practice, 120 bar is sufficient for all plastics and other pipe materials to remove the blockages that form in service.

The same bulletin points to the Sewer Jetting Code of Practice from WRc, the UK water research body, which recommends a maximum of 130 bar (about 1,885 psi), "particularly where the condition of the pipework concerned is unknown or known to be defective." It also favors low pressure with high water volume over high pressure with low volume. A larger nozzle with more water cleans the whole pipe wall, hits the blockage harder, and carries the debris away, with what the bulletin calls minimal risk of damage to pipes.

In the United States, ASTM F3618-22 is the standard practice for jetting PVC, HDPE and polypropylene sewer pipe. It covers operator training, operating procedures and equipment, and it says it should not be applied to other pipe or lining materials without the pipe maker's recommended cleaning procedure.

For most drain and sewer lines, no. It is one of the gentler ways to clean a line, because nothing hard scrapes the pipe wall. A cable machine cuts through a clog with a spinning metal head. A jetter uses water. Phoenix's own crews clean city sewers with a jet hydro-vac truck, which the city describes as essentially a pressure washer with a large vacuum.

The real question is whether the pipe is sound and whether the jetter is matched to it. Chemical drain cleaners are a separate question, which our page on whether Drano is bad for pipes covers.

Four things raise the risk of damage on a plastic line:

• A pipe that is already broken. A crack, a belly where the pipe has sagged, a crushed section or a joint that has pulled apart can open further under a jet. Roots that have grown into a joint usually mean the joint has already opened.
• Thin wall pipe. HotJet USA's guide lists thin-wall PVC with clay and Orangeburg as materials that "can crack or collapse under excessive pressure," especially at close range with a focused nozzle.
• Holding the nozzle in one place. A jet that sits on one spot, a fitting or a glued joint keeps working on that one spot. A good operator keeps the hose moving.
• More pressure than the job needs. HotJet USA says going above 4,000 PSI is rarely necessary for sewer lines. A rental or homeowner rig run hard with the wrong nozzle is where most stories of jetting gone wrong begin. Our page on hydro jetting your own drain pipes covers the risks of doing it yourself.

The gauge on the machine is not the whole story either. Sewer Equipment Co. warns that "just because your pressure gauge says a certain pressure doesn't mean that's what's coming out of the nozzle." Hose length and hose diameter both cut the pressure that reaches the pipe. Our page on jetter PSI versus GPM explains why flow often matters more than pressure.

1. 1Look first. A camera run shows the pipe material, any cracks or offset joints, and what the blockage is. A broken line is a repair job, not a cleaning job.
2. 2Match the setup to the pipe. Pressure, flow and nozzle are chosen for the pipe size and its condition. HotJet USA lists 3,500 to 4,000 PSI at 8 to 10 GPM for 2 to 4 inch residential laterals. Smaller drains inside the house get much less. The nozzle matters as much as the pressure.
3. 3Jet from a cleanout and keep moving. The hose goes in at a cleanout and is worked through the line, not parked in one spot.
4. 4Look again. A camera run after jetting shows the line is clean and that nothing changed.

The same approach works on ABS, the black plastic drain pipe found in many homes. Our page on ABS and PVC pipe explains how the two differ. Older cast iron and clay lines need more care, which our page on jetting old cast iron or clay sewer pipe covers.

A line that clogs again soon after it was snaked, slow drains in more than one fixture, gurgling, or a backup at the lowest drain in the house all point to buildup a cable did not clear. Grease is the first cause. Phoenix's Water Services Department names coagulated grease and cooking oil as the biggest problem in its sewers, with roots from trees and shrubs such as oleanders second.

HQ Plumbing & Air sends a two-person jetting team with a high-powered jetter. The team runs it from the cleanouts to pull grease and sludge out of the line and flush it to the city main. In Phoenix, the sewer line from the building to the public main is the property owner's to clean and repair. See our hydro jetting service and when hydro jetting beats a cable in Phoenix, or contact us to have your line looked at before it is jetted.