[JojoP (OP)]

Hello there,

I'm sorry if this is the wrong place to ask such a question but trying to filter through random google results is getting me nowhere.

I have a stoma (colostomy bag for those not in the know) and I irrigate, or flush out, my large colon daily with water that needs to be around 37.5 degrees. The water has to be drinking quality as it is going into my digestive system, just from the other end, so to speak.

My brother is a heating engineer and warned me that if I don't bring the water up to 60 degrees there is a risk of legionnaires bacterium entering my system and subsequently making me ill.

I have a combination boiler in my home, no standing water tank and so most, if not all of the water from every outlet will be mains-fed.

My question is this: do I really need to wait for the water from the hot tap/faucet to reach 60 degrees to 'kill' any legionnaires, or is it fine to use the tepid water that comes out before it has reached this temperature? I use my water system daily, both hot and cold.

Thank you for your advice, it's much appreciated!

Jo

[Bored chemist]

Legionella thrives at "moderate" temperatures.
I think the best bet us to mix cold (below 20C) and hot water (above 60C) to get water near 37C.
However, don't take my word for it: there must be lots of people facing the same problem and they will have found solutions  and heard the recommendations of people who (unlike me) know what they are talking about.

[Atomic-S]

It seems to me that when the subject of water  purification through temperature has come up, it has been in the course of recommending that it be boiled.  That might be good advice. I am not familiar with your type of water system, but if water is sterilized by heat and then flows into other parts of the system in such a way that it remains sealed against the outside, the drop in temperature at that time would not re-introduce bacteria, so it should still be good. But if heated water uses the same outlet as unheated water, there would seem to be the possibility of contamination. That problem might be solved by flushing out the common section of piping (e.g., faucet) thoroughly, by letting the water from the heated side run vigorously for a short time before actually beginning to use it. 

[Colin2B]

Does your combi boiler take water from the mains supply or from a storage tank?

My understanding is that the legionella grows in water in storage tanks and is unlikely to occur in mains water, perhaps others can confirm.

[JojoP (OP)]

Thank you for your replies, much appreciated.
Colin2B, I don't have a water tank, neither standing or emersion, there is one stop-cock that turns off all water supply to the taps...

[Colin2B]

You might find this useful for accessing your risk http://www.hse.gov.uk/pubns/priced/hsg274part2.pdf sections 2.6 and 2.12 refer to your type of system.

Water from the mains is generally below 20C in temperate zones and this is less of a risk than water kept in loft storage tanks. The risk will depend how long water sits in the system without being flushed through at 55-60C. For my own use I would consider the risk small, but it is worth bearing in mind that depending on the quality of your water supply there are other pathogens that are less easily killed than legionella and internal membranes are very sensitive.

I use a water jet flosser and you have made me wonder if it is wise to fill this from a loft storage tank!