Are you taking a shower with MAC & Others?

We are in process of getting a new hot water heater, ours is very old so these caught my eye. Hubby has been lobbying for a tankless water heater and I think these just pushed me over the edge! The tankless ones are more energy efficient since they are not continually heating water, they are more powerful so they heat it as it is needed.

So the below articles bring to mind a question of how hot can we heat our water with a tankless unit and since its just the water going through the pipes and not sitting in a tank how hot is ideal?

More research to come on that but here is a good article to start:.

http://homerepair.about.com/od/plumbingrepair/ss/tankless_hwh_6.htm

The three variables that have to be considered in sizing and selecting the unit include:


•The volume of water the unit is required to heat, measured as flow rate (GPM).

•The temperature of the cold water entering the unit (this varies by where in country you are)

•The desired temperature of the hot water exiting the unit.
 
 
A tankless water heater is sized by rating its temperature rise at a given GPM.
 
 
http://www.colorado.edu/news/r/50fe20a5a5376631bbad2024f89b02c0.html

50 showerheads from nine cities in seven states that included New York City, Chicago and Denver. They concluded about 30 percent of the devices harbored significant levels of Mycobacterium avium,

During the early stages of the study, the CU team tested showerheads from smaller towns and cities, many of which were using well water rather than municipal water. "We were starting to conclude that pathogen levels we detected in the showerheads were pretty boring," said Feazel, first author on the study. "Then we worked up the New York data and saw a lot of M. avium. It completely reinvigorated the study."


In Denver, one showerhead in the study with high loads of the pathogen Mycobacterium gordonae was cleaned with a bleach solution in an attempt to eradicate it, said Pace. Tests on the showerhead several months later showed the bleach treatment ironically caused a three-fold increase in M. gordonae, indicating a general resistance of mycobacteria species to chlorine.


http://www.sciencenews.org/view/generic/id/37933/title/Science_%2B_the_Public__The_Case_for_Very_Hot_Water


What DOE and other energy-conservation sites don’t point out is that 140 ºF will kill a number of potentially lethal waterborne organisms, like the ones responsible for Legionnaire’s disease and NTM, short for nontuberculous mycobacterial infections. In contrast, 120º provides a nurturing environment for such toxic microbes

What the microbiologist found: The DNA fingerprint of the bacteria responsible the woman’s lung disease “is the same as the mycobacterium in her hot water, cold water and her showerhead.”

The same essentially also occurs in home plumbing. Once piping or water heaters become infected, residual populations of germs take up permanent residence — usually in biofilms. Later, when the flow of water through plumbing is high, such as during a long shower, bits of biofilm can break loose from surfaces, seeding the water with germs. Some cells will readhere to the inside of piping — or your showerhead. Others will just fly out the faucet.

The question now: Will the risks from contaminated plumbing systems diminish if we raise water-heater temperatures back up into the 140 °F range. No test of that has yet been conducted, although Falkinham is itching to start one.