"Sum Guy" wrote in message ...
Ed Pawlowski wrote:

How else could contaminated water flow back into the water supply
system?

Backflow preventers are required by code for lawn sprinkler systems,
boilers that use chemicals, pretty much an process that is connected
to a municipal water supply.

Does that include installing one at your dish washer or clothes washer?

Some towns are trying to do just that. Every home would have one at the
meter. Seems like a rather expensive cure for a non-problem.

I've never heard of anything like it ever happening, but our society wants
to protect us from every possible scenario, not matter how slime the odds of
it happening.