I think last year "this old house" had a device that
monitored waterflow at the meter (or just after) and closed
the supply off if the flow exceeded so many gals/hr. It was
like $200 for the valve and controller. And I think some
areas now require a similar smaller device for the washer
dryer connections, but it only opens the valves when the
washer is pulling electric.

google would be a good place to look ;-)

-larry / dallas