The correct answer is “Never.” A variable frequency drive (VFD) is generally described as a “motor control device that controls the speed of AC induction motors.” A VFD has never pumped a drop of water. Despite this, I hear many people in our industry state that their VFD “pumps 800 gpm”. A VFD is an electrical device that, when connected correctly with a pump, can make that pump behave like a variable speed pump. A pump with a VFD is not a VFD. It is a variable speed pump (VSP). I realize this is a minor point, and most people understand that a VFD is not a pump, but it can be misleading (or at least confusing). Imagine what will happen if somebody tries to hook a VFD to a 12-inch water main. As a matter of clarity, we should not refer to a pump with a VFD as a VFD. I can’t help but get mildly annoyed when someone says, “We have two constant speed pumps and a VFD,” when they should say, “We have two constant speed pumps and a VSP.” We tend to use a lot of incorrect terminology in the water industry, such as saying we

We regularly seek feedback from our users on how we’re doing. In a recent survey, we received excellent scores across the board on our OpenFlows products like OpenFlows Water and OpenFlows Sewer. One individual noted it would be great if Bentley were to “Provide additional training, demos, and webinars.”

In those days, a junior engineer could spend an entire day calculating flows and pressures in a pipe network. At the end of the day, he could show it to his supervisor who would say, “I thought we were going to put a 12-inch pipe over there?” The engineer would look at his boss, look at his day’s work, look at his boss, look at his work again, quietly deposit his work into the trash, and make the required adjustment.

The story of the history of water distribution system analysis (WDSA) is pretty fascinating, at least to me. There have been a large number of contributors to where we are today in water distribution modeling.

We are a water innovation explosion. When planning your water distribution strategy, it should be easy. We recommend starting with digital twin modeling.

It isn’t necessary to explain that customers expect safe, reliable, and affordable water, that distribution systems are a critical link in providing service, that buried and aging infrastructure is a challenge to manage, and that many utilities in the US struggle due to lack of enough funding. These issues are reviewed continually by the water industry to assess what should be done.

with advances in SCADA and digital twins, we are doing a much better job collecting data on pump performance. But what is the best metric for judging pump efficiency?