Reminder 1,063… The Water Level and The Rocks… Remember the Story?

Chatting with folks this week who are really keen about putting Lean to work where they live - brought out again Taiichi Ohno's (Toyota Production System) simple example of how rocks begin to appear as you lower the water level in a river. The water, of course is inventory, and the lower you drop your water/inventory the more you expose the rocks, which are the problems excess inventory hides. The idea is to drop the level so you can find & identify the problems and can fix & remove them one by one until your throughput rockets through your operations, allowing you to achieve ‘high velocity’ mfg. Remember the Basics? First of all, we must understand that all those ugly rocks were already there before the water level is lowered – they are NOT caused by implementing lean. Its like the old timer who sued the drug company because the new sinus spray caused his arm pits to smell - in reality, the drug enabled him to smell what was really there all along.


So - by lowering the water level (inventory) you expose rocks (problems) that were already there but were being hidden by the inventory. And by having a higher level of inventory there is no priority placed on reducing set up times – why would you? It is not ‘urgent’. But as you lower the inventory the problem of set up time surfaces – big time. Therefore, instead of hitting the rock you must remove it. What then are the problems? Namely finding them in the first place so you can then fix them. And once done, lower the water more to eliminate more rocks

1) Not focusing on the right problem in the first place, & 2) Not having any sense of urgency to solve them. If this is present, it will take a long time to solve them… especially since you still have your ten tonnes of coal to get out every day). HOWEVER… if you lower the inventory first, then we are forced to solve these problems immediately.

Ask yourself this question. Which do you prefer?

1) Find the problem, Or,

2) Fix the problem --- and then

3) Lower the inventory

OR… do I

1) begin by lowering the inventory, then,

2) identify the problems that emerge - and then –

3) fix them.

Does not the latter drive the right behaviour’?

One thing folks find as problems come up: there is a tendency to react by adding inventory. Our job is to convince them to solve the problem another way


Otemon’ya Management

This statement was used by Shigeo Shingo, the world renowned manufacturing revolutionary and founder of the Toyota Production System.

In terms of quality, his major contribution was the development in the 1960s of Poke-Yoke and source inspection systems. These developed gradually as he realized that statistical quality control methods would not automatically reduce defects to zero.

The basic idea is to stop the process whenever a defect occurs, define the cause and prevent the recurring source of the defect.

Otemon’ya Management means a system in which plans and instructions are not determined clearly and fully. Immature plans and vague instructions are given out and the rest is left to those who implement them.


The term comes from a Japanese song which says … ”and let the rest take care of itself”


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