What about protection from basement flooding?? In a previous house (where I had an HO scale layout) we got 4 feet of water when the big grid failure in August of 2003 and the following electrical power outage. Everything UNDER the layout was ruined.
Many use a second electrical source- a deep-cell battery and/or a second sump pump. The 2003 outage in the Northeast USA lasted a full two days in some areas. So to be effective, this method assumes regular charging and periodic replacement of the deep cell battery, as well as the reliability of the sump pump itself. Now I have a city water-powered backup system to my electric sump pump. This system has a separate water level sensor (above the electric sump pump float) so that, in the event of an electrical outage or sump pump failure, the city water-powered system through a siphon device pumps 3 gallons out of the sump every 5 gallons of water.
So for the water to flood the basement, we would have to have an electrical outage, and/or a sump pump failure, in addition to no city water supply.
Plus I replace the sump pump about every 5 years.