Please do some serious research about the controversies surrounding the SAFE temperature for your hot water heater, as lowering the temperature MIGHT lead to very destructive health consequences.
Here are two links about this:
MAI Lung Infections
http://www.freerepublic.com/focus/f-chat/1606546/posts
MAY/2006 Indoor Environment
http://www.ieconnections.com/archive/may_06/may_06.htm
Please be cautious, you do not want to damage your lungs with these serious infections.
Hot Water Heater on low may be responsible for serious lung infections
September 28th, 2006 at 10:42 pm
September 29th, 2006 at 01:48 am 1159494520
And it's a shame too, since I'm always trying to find ways to cut my energy consumption.
Anyways, thank you for sharing. I will look further into the matter.
September 29th, 2006 at 09:19 am 1159521565
Do a search for Legionella Temperture
September 29th, 2006 at 11:19 am 1159528756
Since this is really such a new discovery, and it is all very controversial, it's something I want to follow, to see where the scientific evidence leads.
With the feasible possibility that soon there MAY be a world wide avian influenza epidemic, one not Bird-2-Bird, but Human-2-Human infection, I sure don't want my lungs compromised by bacteria breeding away in the hot water heater, not if there's some way to easily avoid it.
November 27th, 2007 at 08:07 pm 1196194025
"In our study, Legionella presence was not affected by the origin of water (groundwater vs. mixture), pipe materials, water temperature, or concentration of chlorine..."
and concludes
"To limit Legionella colonization at the domestic level, we suggest simple and general measures: 1) use independent domestic water heaters, 2) maintain high cleaning standards, 3) periodically replace components of the system which could favor presence or dissemination of bacteria, and 4) have a water copper content >50 µg/L."