Cheaper solution: Don't use the disposal. Use the garbage can or compost the stuff you are washing down the drain.

Great idea Hyenuf. And the solution to dry skin is to stop bathing, right?

OK, let's try this instead. If the sludge from your disposal unit is causing the drain to become plugged you likely are not using enough water while operating the drain disposal. You need enough flow to push the stuff out to the main pipe. I also find it odd that the water from the washing machine fails to clear this out on it's own as that's a significant amount of water.

Hmmmm. . .Maybe you have a sewer pipe problem.

Over the course of the last 35 years, I have had this problem exactly once - in this house only. Yes, it is a design problem, the result of an architectural imperative which is very common in newer homes.

I have solved the problem with 3 products from SmartHome.com (water sensor/interface/plug-in module).

Thank you for your input. We parrotheads must help each other out.

The disposal isn't critical to this idea, just the fact that the washer can't figure out what's going on before it offloads a couple dozen gallons of putrid water. We have a similar situation with our washer, except that the cause hasn't yet been found. Just a puddle when it does go wrong. That, and the washer sometimes stops without a good reason. I'd rather it tell us why, and this reason is good enough as any.

I think this is a good idea, and we could take it one step further. How about a device that senses overflow at any water outlet in the house (sinks, toilets, tubs, etc) and automatically shuts off the water to the outlet? This could prevent very expensive water damage.