Finding the Sweet Spot in Sewer Line Cleaning

KEG Technologies - July 2026

For municipal sewer departments, sewer line cleaning is a routine but critical maintenance function that removes grease, sediment, roots, sludge and other debris before those materials restrict flow, create backups or contribute to larger service disruptions.

Although the work depends on a powerful combination of jetter trucks and high-performance nozzles, effective cleaning still comes down to how well the operator matches the equipment to the actual conditions inside the pipe.

That distinction is important because a high-performance sewer nozzle is a lot like a race car. Both are engineered to deliver exceptional results but purchasing one does not automatically provide the knowledge needed to operate it effectively. Someone accustomed to driving a sedan to work every day cannot simply climb into a race car and expect to get the best performance out of it. The driver must understand how to adjust for speed, track conditions and the capabilities of the vehicle.

The same principle applies to high-efficiency sewer cleaning nozzles. Even an advanced Tier 3 nozzle can fall short of its potential when operators do not understand how nozzle selection, water flow, truck RPMs, pressure and hose travel speed work together.

In practical terms, a Tier 3 nozzle is a high-efficiency sewer cleaning nozzle engineered to control the way water moves through and exits the tool, so more of the truck's available energy is converted into usable cleaning and pulling force rather than being lost to turbulence. Because of that level of fluid, mechanics can make the nozzle seem like the decisive factor, but it is easy to assume that once the right nozzle is installed, the pipe will simply clean itself. In the field, however, the nozzle is only one part of the system.

That is why hands-on operator training alongside the nozzles is so important. The operator still has to dial in the right operating parameters for the specific line being cleaned.

A more effective approach is to find the operating "sweet spot" for the pipe, which requires choosing the best nozzle configuration, flow rate and pressure based on the pipe diameter, hose length, amount of material in the line and other field conditions rather than relying on maximum truck output.

"The goal is to help operators understand what the pipe is telling them, so they can lower the RPMs, control the flow and clean the line in one pass instead of forcing the truck to do all the work," said Dan Story, an experienced trainer and application specialist of KEG Technologies, a Spartanburg, S.C.-based manufacturer of sewer and storm line products.

Story recently demonstrated that approach during a field training session with the city of Pueblo, Colorado. After converting to KEG equipment, the city invited him to spend time with its operators clearing sewer lines and showing them how to get more from the equipment already in service.

The Pueblo crews were initially unsure if the nozzle was working as expected. According to Story, the issue was not the nozzle itself. The operating settings and cleaning technique needed to match the equipment and conditions inside the pipe.

Rather than conduct a classroom-style presentation, Story went into the field with the operators. Together, they worked through actual cleaning scenarios and adjusted the equipment based on what was happening inside each line.

The objective was to demonstrate how changes in RPMs, flow, pressure and nozzle speed affect what is happening underground and how the returning water can give operators the information they need to make better decisions in real time.

Finding the Right Operating Range

Many operators tend to increase the truck's water pressure and flow when they encounter difficult cleaning conditions, assuming that running the equipment harder will produce a better result.

"People think running harder and faster means better cleaning, but it doesn't work that way," said Story.

Excessive pressure can increase friction loss as water moves through the hose. It also consumes water unnecessarily, placing additional strain on the truck and increasing the risk of forcing water or air into residential sewer connections.

During the Pueblo training, Story showed operators how they could reduce engine RPMs and operating pressure while maintaining a strong enough cleaning force. In one exercise involving a line that was notoriously difficult to clean, the crew limited operating pressure to approximately 1,200 psi and carefully controlled the speed of the nozzle.

Story demonstrated that the operators could control the flow at approximately 35 to 40 gal. per minute and complete the work in one pass.

"An 8-, 10-, or 12-inch sewer pipe never needs more than 40 gallons a minute to clean it," said Story. "You have to learn to get that flow down to match the size of pipe you are cleaning."

The correct settings are not necessarily the same for every line. A relatively clean pipe allows the operator to move faster. A line filled with sediment, grease or other material requires a slower approach so the water can break up the debris and carry it toward the downstream manhole.

According to Story, nozzle travel speed for typical sanitary sewer cleaning will often fall between approximately 30 and 60 ft. per minute. Operators must adjust within that range based on the feedback they receive from the pipe.

Reading What Comes Back

Because operators cannot directly see what is occurring underground, Story teaches them to pay close attention to the water and debris returning at the downstream manhole.

"If you pay attention to what comes out of that invert, it is telling you how to clean the pipe," said Story.

The amount of debris, the color of the sediment and changes in the returning flow can all provide information about conditions farther upstream.

When not much material returns, the operator can increase travel speed. When a heavy volume of debris begins coming back, it is a signal to slow the nozzle and give the water enough time to move that material out of the line.

A sudden change in water color also can be significant. If the returning water changes from light gray to black, for example, it may indicate that the nozzle has entered a belly or low section of pipe, where stagnant water and debris have accumulated.

Continuing to force a large volume of water into that area can fill the low section and push water toward nearby service connections. Story instead advises operators to recognize what the changing water is telling them, allow the system to clear the accumulated water and then continue upstream under controlled conditions.

Clean Going In, Rinse Coming Back

Travel direction is another important part of finding the correct balance. A common practice is to send the nozzle rapidly to the upstream manhole and attempt to remove all the accumulated debris while pulling the hose back. This can leave the operator trying to move a large amount of material at once.

"If you shoot the nozzle all the way upstream and then try to clean on the way back, it is like digging a hole from the bottom up," said Story. "Not even a bulldozer can do that efficiently."

Instead, Story teaches operators to clean the line while advancing. Moving at a controlled pace allows the nozzle to loosen material gradually. The existing water flow then acts like a conveyor, carrying the debris toward the downstream manhole rather than allowing it to accumulate behind the nozzle.

"You clean going in," said Story. "Let it stir the material up and let the flow carry it out. As you come back, you should be giving it more of a final rinse."

After the primary cleaning has been completed on the way upstream, operators can reduce pressure and rinse the pipe as the nozzle returns. When the speed and flow have been properly matched to the conditions, the line can be cleaned without sending the nozzle through a second or third time. Using water efficiently keeps the truck working longer before the crew must travel to a hydrant to refill the tank.

Proper technique also reduces the potential for blown toilets and other service disruptions. When a nozzle is sent too quickly through a line, debris may accumulate into a large obstruction that traps and compresses air. As that pressure passes a residential service connection, air and water can be forced through the lateral and into the home.

"Ninety-five percent of blown toilets are operator-related," said Story. "Most of the time it's not the homeowner's plumbing. It's how the line is being cleaned."

Cleaning gradually on the way into the line, using only the water required for the pipe diameter and responding to changing conditions can help operators maintain control of the process. It also reduces the likelihood that a wall of water or compressed air will be pushed toward a service lateral.

Taking Guesswork Out of Field Adjustments

To help operators identify efficient settings more quickly, Story provides a pressure-and-flow spreadsheet that correlates nozzle jetting, operating pressure and expected water flow.

The chart allows a crew to select a nozzle configuration and determine approximately how much water it will deliver at different pressures. Operators can then compare that information with the pipe diameter and field conditions rather than relying on the assumption that higher RPMs or pressure will always improve cleaning.

The chart can be used with nozzles from virtually any manufacturer, provided the operator knows the nozzle's jet configuration.

Story said the reference serves as a practical starting tool for finding the sweet spot. The operator still has to watch what is returning from the line and adjust, but the chart provides an informed baseline for setting up the truck.

For Pueblo, combining that information with field instruction helped the crews see their cleaning process differently.

Leon Marquez, wastewater collection supervisor of the city of Pueblo, sent Story the following message after the training:

"I want to commend Dan Story for the great presentation and information he gave to me and my crew in Pueblo Colorado. The techniques and information he instructed helped my crew tremendously to save water, work more efficient, and see our process in a better way. Thank you Dan for the expertise. This is not our first time and hopefully not our last time having you instruct us."

The Pueblo experience illustrates why the nozzle itself is only one part of the cleaning system. When operators are trained how to find the sweet spot and learn to read the returning water, they can reduce repeat passes, avoid unnecessary wear on the truck and lower the risk of service disruptions.

For more information, visit kegnozzles.com/.