One of the things that keeps Lean manufacturing from being boring to the amateur linguist is the many odd-sounding words that make up the Lean lexicon. Kamishibai. Heijunka. Pareto. Yamazumi. Takt. Andon. Jidoka. Kaizen. Pokayoke. Gemba. And don't even get me started on the acronyms.

Then there is this thing called the Water Spider. The Water Spider position is often confused with a simple material handler or an entry level "go fetch" person. Far from it, the Water Spider needs to be thoroughly familiar with the materials, tools and methods of the process they are supporting. My teachers used to say the Water Spider role was a "right of passage" to becoming a supervisor. The Water Spider is an honored and critical role in making continuous flow and a smoothly functioning Lean system a reality.

But what's in a name? Why Water Spider? People often think this word comes from the insect that skims the surface of the water (water strider) but technically this is not correct. The water spider is the beetle that moves about inside the water, not on the surface. What makes this confusing is that the word "mizusumashi" in Japanese at times refers to both.

A good way to remember this is that while the water beetle dives into the water (dives into the process, gets close the the cell, even goes into the cell to do occasional relief work for operators) the water strider skims across the surface and does not go under the water (close to the process). The Water Spider in Lean manufacturing must be intimate with the process or cell they support, not just a pick-up-and-drop-off material handler.

Who cares? Is this distinction important? Why are we talking about beetles?

The similarity between the Water Spider (the person who moves about the factory or assembly line) and water beetle (swims under the water) was explained to me as how they move in the water or move about the factory. This explanation by itself might lead to the misunderstanding that the Water Spider is a typical material handler.

But here's another theory. Water spider is “mizusumashi” in Japanese. This is written phonetically as みずすまし or in kanji script as 水澄まし. The word literally means "make water cleaner" or "purify water". I don't know if this little beetle actually cleans the water or not. You would have to ask an entomologist. The water beetle does have little broom-like fibers on its rear legs, so perhaps that's how it "cleans the water". Or perhaps it was noticed that water spiders only lived in the clear water so they were given credit for making it clean.

If we suppose that the water spider (beetle) makes the water clean or keeps it clean, the water spider (human) also keeps the flow in the factory or in the flow line clean and smooth by taking on the occasional tasks (tasks that do not happen every cycle, such as material replenishment or making shipping containers). A clear process flow and defined work sequence (clear flowing water) is also a requirement for designing the workload of the Water Spider position.

So let's have a look at these little clear water bugs. They look a bit like cockroaches so don't follow these links if you are squeamish. Here is a glossy black water spider swimming in the water. Here is a more colorful water spider posing for the camera. This water spider is resting (cockroach alert) on a piece of wood sticking out of the water.

Mike Wroblewski at the Got Boondoggle? blog wrote a great entry a while ago about his personal experience doing the work and doing kaizen of the Water Spider job. Check it out.

The Water Spider role is very important and there is a lot more that could be said about the Water Spider in Lean manufacturing, but perhaps another day.