2009 IPC; hand washing temp

happy new year!

per section 416.5 tempered water is required in public restrooms for hand washing. by definition, the water temperature is to be between 85-110 degrees F.

since the tap water here is generally found to be about 80 degrees F, there is some question as to the need to heat the water.

does anyone know why 85 degrees was chosen to be the low temperature requirement? at that temperature, does it kill of some bacteria or something? appreciate you wisdom on this!

Original Post
What is the correct temperature for water at handwashing sinks?
Water should be at 100 degrees F or hotter. There is no provision in the NC Foodservice Rules that requires water to be at 110 degrees F. Here are the requirements for lavatory facilities in foodservice operations as they appear in the NC Rules.

(a) Lavatory facilities, including hot and cold running water and a combination supply faucet or tempered water and sanitary towels or approved hand-drying devices and soap, shall be provided for employees and customers.

(b) For employees, at least one lavatory shall be provided in the kitchen area in addition to any lavatories, which may be provided in employees' toilet rooms.

(c) Dishwashing sinks, vegetable sinks, and pot sinks shall not be used as handwashing facilities.

(d) The lavatories shall be kept clean and in good repair.

However, foodservice establishments are advised to get hot and cold water lines at hand sinks or to accept tempered water if that is the facilities' choice. Tempered water is, by the Plumbing Code water that is between 85 and 110 degrees F.

The U.S. Food Code (2005) provides a temperature standard for handwashing sinks. The Food Code states a handwashing sink shall be equipped to provide water at a temperature of at least 100 degrees F through a mixing valve or combination faucet. This is the standard used in the NC School HACCP template because it is based on the U.S. Food Code (2005).
5-202.12 Handwashing Sink, Installation.
(A) A HANDWASHING SINK shall be equipped to provide water at a
temperature of at least 38oC (100oF) through a mixing valve or
combination faucet.
(B) A steam mixing valve may not be used at a HANDWASHING SINK.
(C) A self-closing, slow-closing, or metering faucet shall provide a
flow of water for at least 15 seconds without the need to reactivate
the faucet.
(D) An automatic handwashing facility shall be installed in
accordance with manufacturer=s instructions.
Posters appear to be conflating two different issues... standard public restrooms (the subject of the original post) and either food-service or medical uses.

First, is it any wonder that various codes are not in full agreement? Multiple agencies issuing isolated regulations without coordination. Gee, where have I seen this before?

Second, without knowing the history, the most likely reason for the temp range was 'compromise' among those sitting at the table, not based on science. (Read that to say - throwing darts at the wall.)

Latest studies (came across this in major media maybe within the last month - if I recall correctly it was Harvard or another major university study) regarding public restroom use and effectiveness in combating common bacterial spread and infections concluded that there is no substantive differential in hand/skin bacterial count before and after ordinary washing in public restrooms whether using soap or not, and regardless of water temperature.

Given this, the question should not be what temp is best for public restrooms. The real question is whether there is any supportable rationale for a code dictating a temperature in the first place (if not scientifically determined).

Apparently you get as much benefit from a simple rinsing with cold water as you do from adding soap or changing temperature. That is not to say soap does not remove surface 'dirt' - it does - rather that it is not effective in altering the bacterial environment in the surface layers of the skin.

As an alternate to lavatories, studies were also done on effectiveness of the squirters with anti-bacterial liquids, and these were also found to be pretty much non-effective. They are mostly a placebo (and have made millions/billions on nothing more than scare tactics).

But since this is based on science and not 'emotion' or business lobbying (by manufacturers and installers) it is unlikely code writers will take the science into consideration.

The biggest factor in providing warm/tempered/hot water in public restrooms is more closely related to 'comfort' (not having to wash hands with ice cold water in cool climates) than it is to fulfilling the purported function of decreasing bacterial growth/spread. Of course, the idea of using hotter water is ancient - and old concepts (bubba meiser, if you understand yiddish) don't die easily.

That said, I have no good answer on what to use as the standard under current code - and wouldn't want to be the crusader that goes up against the system using science v. tradition.
Do you have some links to those studies on handwashing and water temperatures /soap use? I admit much confusion on this issue as well, especially in the education arena: Many school clients do not want to maintain water heaters.

My own observation is that my hands feel cleaner if I wash with soap and hot/warm water, and that it seems to be easier to remove dirt, but I don't know the science behind it at all.

Beyond that, use of more comfortable /warmer temperature water would likely [again only opinion here] seem to encourage hand washing to be more thorough or perhaps a little longer in duration.

sorry i don't have info/recall on the studies... in trying to remember the source, it might in fact have been a part of a continuing education course taken in last couple of months... would have noted it had i thought this might come up as a discussion item... just don't have time/energy to keep up with everything i come into contact with

i agree warm/hot water 'seems' to be helpful for reasons you indicated, and in connection with surface dirt, etc... but the point of the studies is that this didn't substantially alter the bacterial environment of the skin when comparing counts before and after washing...

so when thinking about 'code', the point i was getting at is that codes are supposed to be what is 'required' for health and safety... if hot water does not further public health, then it has no place in the code...

if on the other hand hot water is 'good' as a best practice, as something that is desired, as something that clients and building users expect and/or demand, then it's something designers should take into consideration... that is quite different than 'requiring' it by law...

so should the design/construction/development community have an option, or should it be mandatory... presently it is required...

our codes are, unfortunately, burdened with numerous such items that may be desirable but do not actually improve public health and safety (the purported SOLE purpose of the codes in the first place)... we've chatted about many such items over the years on this board

I doubt the 'structure' of codes will change in my lifetime... because code-writing has become its own 'industry' that is perpetuated by constant changes (for which updates the ICC can charge us all), there is no impetus to cut back... in fact the number/type of codes in recent years has literally exploded, with no end in sight... codes no longer address only health/safety, but are used to promote public policy (i.e. sustainability/green, and others)... and of course as codes become stricter and more complicated, and construction costs (for compliance) rise accordingly, the product manufacturers and trade groups also smile because it means their profits will increase

as usual, follow the money...

my advice is that if you are working on a current project, or advising a client on near- or medium-term projects, assume you will need hot water and bite the bullet on costs... even if codes were to change later, the ultimate users of the facilities will still enjoy a better-built environment...

In a 2005 report in the Journal of Occupational and Environmental Medicine, scientists with the Joint Bank Group/Fund Health Services Department pointed out that in studies in which subjects had their hands contaminated, and then were instructed to wash and rinse with soap for 25 seconds using water with temperatures ranging from 40 degrees Fahrenheit to 120 degrees, the various temperatures had “no effect on transient or resident bacterial reduction.”

They found no evidence that hot water had any benefit, and noted that it might increase the “irritant capacity” of some soaps, causing contact dermatitis. “Temperature of water used for hand washing should not be guided by antibacterial effects but comfort,” they wrote, “which is in the tepid to warm temperature range. The usage of tepid water instead of hot water also has economic benefits.”


Hot water for hand washing has not been proved to remove germs better than cold water.
greetings all!

just got word from the ICC. in short, they do not know why 85F was chosen as the lower limit. in fact, Florida's 2010 made a similar amendment to not require hot water (unless required by other law or codes, for health, food, etc.).

appreciate all your input and information.
two questions arise:

1. Does that mean ICC intends to eliminate the hot water requirement?

2. How many other code requirements will ICC admit have no underlying justifiable rationale and could be eliminated?

Maybe ICC should be challenged to go through every code book and identify each provision for which it cannot prove 'why' it exists as written.

When pigs fly.

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