We are exploring using single-pipe 75 degree water in outpatient clinics, and our focus is on improving infection prevention. Our strategy is to use a separate heating system for the tempered water than for the hot water. The advantage is that by never getting the water too hot, the chlorine level provided in the municipal water supply continues through the system. I am curious if anyone has any thoughts on that. Right now, we see the benefits for infection prevention as follows:
1. Dead legs are reduced by 50%
2. The number of angle stops are reduced by 50%
3. The water stays below 77 degrees
4. The water stays chlorinated
We are also looking for reasons not to do this, and we are coming up empty. 77 degrees does not feel too cold, and may be more consistently delivered. This morning, I checked a two-pipe sink that I know can be cold and the water was 67 degrees. This feels like cold water, where the 77 degree water feels like tempered. Are there any reasons why we should not do this?
thanks
Paul - So sorry I missed this for so long.
We did do this in a medical office building here in the Bay Area. We heated the incoming cold water to 77F, then distributed that to the handwashing fixtures. There is a second conventional hot water system for showers. The building maintenance staff received some questions from users as to whether they were supposed to be able to get "hot" water, but I'm not aware of any complaints.
One reason not to do this is code-compliance - depending on which model code your under. The IPC requires hot water at a temperature equal to or greater than 110° F for “bathing and washing purposes” in commercial buildings. That is generally interpreted by AHJs and design engineers to include handwashing. One might assume this minimum temperature is codified either to ensure comfort for bathers, or it is an unexamined assumption that it is effective in preventing growth of pathogens in piping and/or the removal of bacteria from hands.
The UPC states: “Hot and Cold Water Required. Except where not deemed necessary for safety or sanitation by the Authority Having Jurisdiction, each plumbing fixture shall be provided with an adequate supply of potable running water piped thereto in an approved manner, so arranged as to flush and keep it in a clean and sanitary condition. …” The UPC defines “hot water” as exceeding or equal to 120° F. The UPC does not clearly require hot water for handwashing fixtures; however, in my experience, AHJs generally interpret the code’s intent as having the water up to each fixture hot enough to limit pathogen growth and that further code provisions, such as mixing valves, prevent water over 120° F from leaving the faucet and creating a scald risk. It appears to me the intent is that if you are going to provide hot water to a handwash fixture, you must have a minimum temperature serving it to prevent pathogen growth, and you must have a maximum temperature leaving the faucet to prevent scalding.
We have proposed this system to several clients at this point. The most common reason they don't go for it is that they expect it will bring a long future of complaints from users. I'm hoping this expectation for extra comfort will erode as more of us understand the environmental and maintenance cost of this nice-to-have".
I think we can make this work, Brian, but the initial focus is on infection prevention, not carbon reduction. We reduce the number of valves, make it much easier to flush out the system and keep the chlorine in the system, so it is better for infection prevention and just happens to be cheaper at the same time. I can sell that idea to end users, who seem to accept 75 degrees as a normal handwashing temp.
Interesting is the culture we are battling. We are having success in PA, but not yet n FL, where there is more opposition. The ambient temp of water coming out of the municipal water system in FL is 72 degrees Fahrenheit. Go figure....
Paul - I do agree - the less real estate for pathogen growth, the better. I spoke with an infection control professional from a Florida facility a couple years ago. Their "cold" water comes in at +80F sometimes. If that system served toilets and hand wash fixtures, and its right-sized, it would eliminate a lot of stagnation and water age issue many systems have.