Service Truck Inventory Management: How Katy Plumbing Stopped Resupply Runs and Regained $1-2M in Revenue

Anthony Johnson at Katy Plumbing & Heating put it plainly: "We're not in the parts business. We're in the plumbing business." Before they implemented service truck inventory management software, techs were making daily supply house runs that were costing the company an estimated $1–2M a year in unbilled time. Here's the system they used to fix it, and what it took to make it stick.

I've talked to a lot of service company GMs over the years, and there's a version of this story I hear constantly.

A technician finishes one job. He needs a part for the next one. He doesn't have it on the truck. So he drives to the supply house, waits in line, and kills an hour or more before he touches his next job.

Multiply that by 30 techs. Multiply that by five days a week.

That's not a parts problem. That's a revenue problem.

The Real Cost of Emergency Supply Runs for Parts

Anthony Johnson oversees operations at Katy Plumbing & Heating in Katy, Texas — a 26-year-old family business. He described the supply house dependency plainly:

"Back in the day, they'd probably be in the supply house once a day, at least. When you go to the supply house, it's an hour, an hour and a half — there's a line, those guys are never in a hurry. We're not in the parts business. We're in the plumbing business."

The financial incentive to fix that was significant. Katy Plumbing has calculated that by keeping techs on jobs instead of running to the supply house, they're able to bill approximately $1–2M more per year in technician time. Their warehouse manager's overtime has dropped by an estimated $45,000 per year. And inventory counting that used to consume 3 hours every day now takes 3 minutes.

The Model That Works To Stop Resupply Runs

The fix is structural: build your own internal supply house and make the external one unnecessary.

Every truck carries stocked inventory tied to minimum and maximum quantity levels. When a tech uses a part on a job, he logs it in a work order. When inventory drops to the minimum, a replenishment order is generated. The warehouse restocks the truck with a bin of the needed parts for each tech. The tech picks up fresh material before his first job the next morning.

Anthony described what that daily rhythm looks like:

"Every day — they put in work orders, the bins get restocked. They pick up the material the next morning and they don't have to spend time chasing around parts. We're able to keep them out of the supply house almost totally."

Before this system, his techs were at the supply house at least once a day. Now it's nearly zero — reserved only for specialty parts they don't stock.

Three Things to Get Right

Individual truck tracking.

Each technician logs usage against their specific vehicle. You know what's on every truck in real time — not just what was loaded last week. Anthony noted that this visibility was a core requirement: 

"We needed it where each plumber has their own individual login and they can use material on their specific truck. We know exactly what we have on each truck."

Honest min/max levels.

The most common mistake is setting min/max levels too high out of fear of stockouts. Start lean and let real usage data guide adjustments to your min/max inventory management. Most companies find they can reduce truck inventory significantly once they're actually measuring it.

Katy Plumbing estimates the service truck inventory management software helped them stock 5% less inventory, saving them $750,000.

A centralized warehouse as the hub.

Distributors replenish the warehouse. The warehouse replenishes the trucks. Techs never need to leave a job to find a part.

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The Change Management Reality: How They Got Techs to Use The New Service Truck Inventory Software

The harder part of rolling out truck inventory management isn't the software — it's the behavior change. Anthony's techs pushed back. Some had been doing things the same way for 20 years.

His approach: remove the alternative:

"We wouldn't allow them to use any other way to order their parts. There's no other way for them to get their material."

Within about 18 months, the resistance was gone. The system became second nature — not because he convinced everyone it was a good idea, but because there was no other option. When the only path to getting parts is through the system, adoption follows.

What Katy Saved In Inventory Costs

Anthony estimates Katy Plumbing has saved approximately 5% of net revenue, or $750,000 since implementing service truck inventory management. His techs are no longer burning hours at the supply house. His warehouse manager isn't hand-counting parts or running emergency deliveries to job sites. And for the first time, he can see exactly what's on every truck in real time.

Bill Kennedy, Katy Plumbing's Warehouse Manager, said it directly:

"With the amount of techs I have to provide parts for, research parts for, and deliver parts to — I would be sunk without eTurns. Instead of 9 to 10 hour days, I would be putting in 12 to 15 hours at least."

Field Service Software Doesn't Solve This Problem, Service Truck Inventory Management Software Does

One clarification worth making for GMs evaluating their options: if you're already running field service management software — ServiceTitan, Housecall Pro, or similar — that system is essential for dispatching and invoicing. But it doesn't manage what's physically on your trucks very well.

Field service software tracks tasks. Service truck inventory management software tracks parts — what's on each vehicle, what's been used, what needs to be replenished using min/max levels, what needs to be transferred, and what it's costing you. These are two different problems. Most service companies solve the first and ignore the second. The companies that solve both are the ones that stop losing revenue to the supply house.

Are your techs still making emergency supply house runs?

Until next time,

Rock

Rock Rockwell is CEO of eTurns, maker of TrackStock — inventory management software for service trucks and point-of-use stockrooms. If you're running service trucks and want to see how min/max replenishment would work for your operation, book a demo here. Sign up here for his Linked In Newsletter: Modern VMI Tips