I was recently fiddling with the settings on our Fischer & Pykel oven
and came across the Sabbath setting. It is there so the oven cannot be
used on the sabbath.
I had read how Orthodox Jews cannot use electricity on the sabbath but
I never saw whether they can make use of the sewage system on the sabbath.
One Saturday I was about 25 feet up a mast in my backyard struggling to
get an awkward antenna into position, and in next doors yard my neighbor
was sitting in the sun reading. They were Seven Day Adventists.
He said to me, "I will give you a hand tomorrow if you like".
My thoughts were one thing, but I said, "No matter I will get it right soon".
As far as electricity is concerned, if the power stations were to close
it would take a day to shut down and a day to start up again. So three
days would be lost !
If various religious groups wanted their days observed it would mean no
power for five days a week ! hmmm.

It does illustrate the absurdity of those rules in a modern society.

Dear Bazz,

«I had read how Orthodox Jews cannot use electricity on the sabbath but
I never saw whether they can make use of the sewage system on the sabbath.»

Orthodox Jews CAN use electricity on the Sabbath, provided they do not turn electrical devices on/off or change their settings. It is OK however for settings to be changed by automated devices (such as by thermostats), by small children (so long as they are not told to do it) or by non-Jewish people (without instructing them explicitly during the Sabbath). Sewage normally operates by gravity, not by electricity.

There are also some valid technological tricks to bypass some prohibitions - enjoy:
http://www.youtube.com/watch?v=NdbkvJznmwU
http://www.youtube.com/watch?v=dQf2l8RxJaE

If you are interested in the legal nitty-gritty:
http://www.youtube.com/watch?v=_WVIBap9wYU
http://www.youtube.com/watch?v=FL-l6qUiqCQ

But if you are looking for the spirit of things:
http://www.youtube.com/watch?v=SSDvJw1H8fE