Thursday, November 17, 2011
Kosher Water Meter
"The Torah commands us to rest on Shabbat, along with our families, workers, and animals. There's nothing on that list about digital water meters, but the halachic issue is indeed there. And that's a big problem (my emphasis) in the modern world: Digital meters measuring electricity, water and gas are essential to the infrastructure of smart homes and smart cities that are becoming more and more common.
The halachic issue of “closing a circuit” (segirat ma'agal) is one of the reasons that digital meters are not more common in Israel. A Sabbath observant person cannot open the water tap on Shabbat, because the information in the meter is updated, as is its display, with every drop. This is not the case with mechanical meters, which measure usage indirectly (as water flows it drives piston or disk that moves a magnet which in turn drives the register.