Hydro-jetting

How it is different from a cable

A jetter sends water down a hose to a nozzle with jets angled backwards. Those rear jets pull the hose up the pipe against the flow, and on the way back down they scour the wall for the full circumference. That is the difference: a cable makes a passage, a jet restores a diameter.

Two numbers describe a jetter and people quote the wrong one. Pressure — psi — is what cuts through a plug. Flow — gallons per minute — is what carries the debris away once it is cut. A high-pressure, low-flow machine will punch a hole in a grease plug and leave the material in the pipe. On a four-inch residential line, flow is usually the thing that decides whether the job holds.

What it is right for

• Grease. Kitchen and restaurant lines, where the problem is the wall and not the middle.
• Sludge and paper build-up in a long, flat run that has slowly lost diameter.
• Sand and silt, which cable straight through and leave behind.
• Scale in cast iron, with the right head — and usually after a chain knocker rather than instead of one.
• Roots, after they have been cut, to wash the cuttings out instead of leaving them in the low points.

What it is wrong for, and this is the part that matters

You do not put a jet down a line whose structural condition is unknown. A jet is a tool that finds the weakest point in a pipe, and on sixty-year-old clay with an open joint, or on cast iron that has channelled through at the invert until it is paper-thin, it will find it. What was a slow drain becomes an excavation.

So on any line old enough to be in question, the camera goes first. If the camera shows a joint standing open, jetting that run gets declined until the joint is repaired, and it gets declined in writing with the reason, not quietly left off the quote.

The other honest limit: a jet cleans a pipe, it does not change its shape. Jetting a bellied line gives you a very clean sag. The water still stands in it the following afternoon.

And the debris has to have somewhere to go

Everything a jet takes off the wall travels downstream. If the downstream end is a city main, that is fine. If it is a septic tank, you have just sent a winter of sludge into it and the tank needs to be in a condition to take that. If there is a second restriction further down, the material stops there. We look at where it is going before we start, which occasionally means the answer is “not today”.