Rob Welke is an Australian water professional with 50 years of experience split nearly evenly between the municipal and irrigation sectors. Throughout it all, he has focused on energy efficiency, and his experience has led him to look past just the pump to the system as a whole. Through his company, the WATER PUMPING INSTITUTE, Mr. Welke runs a Pumping System Master Class for irrigators that helps them put precise numbers on the energy use and cost savings of running their pumping systems. In this interview, Mr. Welke explains the concepts behind the course and lays out its advantages for irrigators. 

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Irrigation Leader: Please tell us about your background and how you came to be in your current position. 

Rob Welke: I started my life out on a wheat and sheep farm in Mid North South Australia. One thing that defines me most is that my father always said, “Don’t follow the world; create your own.” That’s exactly what I’ve done. I spent three parts of my career following others, but I didn’t feel that it was right, so I’ve gone and created my own company and training course. 

I started my tertiary education studying technology and mechanical engineering. I later did some training courses with Irrigation Australia, a sister company of the Irrigation Association in the United States that also provides training and assessment qualifications. I was a member of the American Society of Irrigation Consultants for a number of years, and I’m currently a member of Irrigation Australia and Pumping Industry Australia. I’ve spent 53 years in pumping and hydraulics, the last 50 as a paraprofessional mechanical engineer. Paraprofessional means just under the full professional level but having most of the attributes of a full professional engineer. 

At the point at which I stopped my bachelor of technology studies, I went to an employment agency and said I wanted to do a fitter and turner’s apprenticeship. I was matched with the government engineering water department, which is now called SA Water. Within a short time, I was attached to the pumping engineer. My principal role was to monitor the energy efficiency of all our major pumping plants. We’re talking about 175,000 horsepower of pumps, up to about 7,500 horsepower each, and pipelines up to 1.6 meters (5.25 feet) in diameter. 

To put this into perspective, South Australia is the driest state of the driest continent in the world. It is heavily reliant on pumping. In a dry year, South Australia’s capital city, Adelaide, which has a population of 1.5 million, requires 90 percent of its water supply to be pumped 60 miles from the River Murray over 1,200‑foot ranges. Five major pumping schemes supply this water. 

After 25 years with SA Water, I went into the irrigation industry. I deliberately chose it because I wanted to pursue a career in promoting energy efficiency in an area where people were listening more, and I saw a real opening in irrigation. Over the last 28 years in irrigation, I’ve conducted a lot of energy audits of pumping station and pumping system designs. You could say that throughout the last 50 years of my career, I’ve had a pressure gauge in one hand and a flow meter in the other. It’s also significant that I’ve never sold product. That makes me quite unique in the irrigation industry. 

Irrigation Leader: What are the components of your pumping master class? 

Rob Welke: As a result of what I learned through experience during my many audits, I came up with a whole gamut of things that I thought the irrigation industry should know that weren’t being taught or practiced. There are four units to the course, which take about 3½ hours each over 4 days. 

I start off talking about energy and how we apply it. Then I go into pipelines. Pipelines are obviously conduits for water, but they are subject to deteriorations in performance. Knowing what to expect and how to quantify that is important. Then we go into the selection of pumps and other components inside a pump station, targeting energy efficiency the whole way. This course is about energy efficiency, which can save end users thousands of dollars a year. 

Then we look at pump testing, which is not as easy as you might think. Pump testing deals principally with flow measurement. I’ve always said that the accuracy of a pump test is 90 percent determined by the accuracy of the flow meter. 

This course is predicated on the fact that selecting the most energy-efficient pump is only the first step in maximizing pumping system efficiency. All pumps these days are very efficient, so what’s the difference between pump efficiency and pumping system efficiency? The answer lies in the hydraulic efficiency of the whole pumping system. Basically, the overall energy efficiency of a whole irrigation system has little to do with the pump—it mostly has to do with the hydraulics, and when it comes to hydraulics, the pipeline is the most important. 

This course considers pipelines as much a part of energy efficiency as pumps. When it comes to pumps, we look at how efficient they are and how much energy we can extract from them as their efficiency goes down. With the pipeline, we look at how much energy is required to overcome the friction, and then we quantify it in terms of pumping cost dollars. If we can quantify a pump in terms of dollars to run, we can also quantify a pipeline in terms of dollars to run. 

It’s a simple parallel, but some significant science goes into figuring out those numbers, and the course bears that out. These numbers are not based on speculation; they are based on my career outcomes. I’ve done five major audits of irrigation systems through government agencies in Australia, each of which took 2–4 days. I zeroed in on hydraulic efficiency and how to optimize systems to reduce the running costs of a pumping system. I found that optimizing pump efficiency represented only 17 percent of the potential savings that could be derived from optimizing an irrigation system, while optimizing hydraulics represented 33 percent of the savings. That’s twice as much! There are hundreds of pumping systems out there that can and should be hydraulically optimized to save growers thousands of dollars annually in pumping costs. 

The course is really about the software. The software empowers the participants to convert the losses in their systems into savings. The software is all Excel spreadsheets, but some of them have been converted into phone apps. 

One of the most useful pieces of software is the Pump Data Calculator. You enter the pumped head, the cost of the electricity tariff, and the volume of water, and the program calculates an annual pumping cost. Then, it amortizes the cost over 25 years at a given electricity cost index and inflation rate to calculate an amortized electricity cost. Then, we can start to evaluate friction losses not in terms of feet head loss or pounds per square inch but in dollar amounts. From there, we can start to ask how much we can reduce those dollar amounts. 

For pipelines, we’ve got our Pipe Suite, which is a suite of 13 calculators. During my extensive time in the field, I wished I had had a calculator to do some simple calculations. In the end, I created my own, which is now available as a phone app. Another app, HYDRopz, is a hydraulic optimizer. It calculates the optimum pipeline size based on energy efficiency. If there’s one thing that this course will teach you, it is that pipe sizing according to energy efficiency is quite different from pipe sizing according to irrigation efficiency. With irrigation efficiency, we’re talking about a velocity limit of 5 feet per second, but it’s much less when it comes to energy efficiency. In February 2021, the national energy engineer from the U.S. Department of Agriculture, Terry Ruch, attended my course. At one point, she said, “You know, the 5 feet per second was never intended as a guideline for energy efficiency. It was only ever intended for water or irrigation efficiency.” So we’re operating in a new paradigm; this training course is a world first. 

The flagship software of the course is our elaborate pump selection software, which has numerous system curves. There just isn’t anything else like this out there. Last, we have pump testing software, which is really useful. 

Each of these software programs comes with a tutorial, and I demonstrate them during the course. I create hypothetical scenarios based on my experience that show people how to use the programs. 

In summary, this course teaches people how to design pumping energy efficiency principles into new irrigation systems and to fix old ones. It redefines pumping energy efficiency for irrigation, moving away from the old paradigm in which you just look at the pump. The pipelines are where the big gains are. 

Irrigation Leader: So everyone who takes the course also gets the software? 

Rob Welke: Absolutely. Every person who attends gets a copy of the software and is taught how to use it in the class. For software that is available as a phone app, I show them how to load it onto their phones. I developed the software myself to use in projects that I’ve done over the last 20 years. I’ve modified it to make it user friendly for the course. My estimate is that about 1,500 hours of time has gone into the production of this training course. That’s my time, you know—whereas most people will be watching football on a Saturday night, I’ll be tinkering with a spreadsheet. That’s what I like to do. 

Irrigation Leader: Does your business offer activities and services other than this course?

HYDRopz, WATER PUMPING INSTITUTE’s flagship software, determines optimum pipe diameters for energy efficient pumping.

Rob Welke: This course is my main focus, but I still do energy audits. For example, I’ve been asked to review the specifications for a $2.5 million pipeline scheme. People still come to me for my expertise in that area, and I enjoy getting involved in projects like those. 

Irrigation Leader: Who is the audience for the course? 

Rob Welke: When I started out with this, my target was growers, because they are pocket sensitive to the cost of energy. Ultimately, I found that growers tend to be spoiled rotten with government-subsidized training. Generally, they don’t have to pay any money to be trained. Because my course is not part of a national curriculum, it doesn’t attract free funding, so everybody has to pay, and therefore farmers don’t want to come. That’s a tragedy, really, because it’s focused for their benefit. As a result, I decided to target farm managers, branch managers, and designers. These professionals can filter this information down and handpick people they think would benefit from this course. 

Irrigation Leader: What are the main blind spots that you’re trying to correct with this course? 

Rob Welke: Almost anything that goes beyond the pump itself, but the big one is the pipeline. You know, I’ve heard people say, “I’m only going to install a 6‑inch pipeline, because that’s all my father ever installed.” People think they’re saving money by doing this, but they’re setting themselves up for long-term loss by selecting excessively small pipes. This course puts numbers in front of people that make them say, “You’re right. I do need a 10‑inch rather than a 6‑inch pipe.” 

Irrigation Leader: Aside from size, what makes a pipe more or less energy efficient? Does material play a role? 

Rob Welke: The majority of the pipe used in the irrigation industry is PVC or poly, both of which have an almost mirror-like finish on the inside. New pipe is very efficient if it’s sized correctly, but it will still have high friction if you push too much velocity through it. The first step is to size the pipe according to the optimum level of friction. HYDRopz does that. 

Throughout the life of the pipeline, under certain water conditions, algae or biofilm can build up in the pipe, increasing pipeline friction and therefore increasing energy expenditures. We need to allow for this in the design process. Biofilm is only a few thousandths of an inch in thickness, but it significantly affects pipeline performance. For example, you can expect a 10 percent reduction in pipeline efficiency within the first year when running recycled water through a pipeline. And if you take water that has picked up bacteria from a channel system, it can grow algae that sticks to the inside surface of the pipe and significantly increases pump power requirement. 

Irrigation Leader: How many participants are usually taking part in the course simultaneously? Do participants get personalized attention? 

Rob Welke: I encourage people to raise their hands right in the moment when they have questions rather than waiting till the end of the session. Maybe some of the others have the same question. To enable that, I prefer a smaller class. I don’t like going over 12. In the case of face-to-face classes, I’ll go up to 16. With numbers beyond that, people are not inclined to ask questions, and if you don’t ask questions, you don’t get the maximum from the training course. 

Irrigation Leader: What practical information should readers know about the course’s length and cost? 

Rob Welke: The course costs US$595 and lasts 4 days, 3½ hours a day. The next course sessions are February 14–17 and March 28–31. The course is worth 8 continuing education units from the Irrigation Association, and it comes with a certificate of completion. We encourage large groups to have in-house training so there’s no conflict of interest within the class. Separate class times can be arranged for anyone with a large group. Interested readers should visit our website at for more information. You can easily register for a course and pay with a credit card at As a service to Irrigation Leader subscribers, we will give away a free phone app software to the first six e-mail inquiries about our Pumping System Master Class. 

Rob Welke is an independent consultant. He can be contacted at or +61 414 492 256. When calling from the United States, it is best to try after 6:00 p.m. U.S. time.