A Health Hazard for Systems without Backflows?

6/3/2026

Are there incidents of actual water health hazards from fire sprinkler systems?

I try to avoid waste. Backflow prevention devices are costly and also make sprinkler systems more expensive by adding friction loss, which can mean larger pipes. The water in most sprinkler systems is the same water as in the domestic system. Yes, the water in a steel pipe sprinkler system will get brown over time, because it picks up iron. Not pretty, but is that iron a health hazard? People buy Iron supplements.

In California the laws are confusing. Health and Safety Code - HSC § 13114.7 states: (b) Automatic fire sprinkler systems described in subdivision (a) shall not require any backflow protection equipment at the service connection other than required by standards for those systems contained in the publication of the National Fire Protection Association entitled “Installation of Sprinkler Systems” (N.F.P.A. Pamphlet No. 13, 1980 edition). and (a) states: (a) For the purposes of this section, the following are definitions of class I and class II systems:

(1) American Water Works Association (A.W.W.A.) Manual No. M-14 class 1—Automatic fire sprinkler systems with direct connection from public water mains only; no pumps, tanks, or reservoirs; no physical connection from other water supplies; no antifreeze or additives of any kind; and all sprinkler drains discharging to the atmosphere or other safe outlets.

(2) American Water Works Association (A.W.W.A.) Manual No. M-14 class 2—Automatic fire sprinkler systems which are the same as class 1, except that booster pumps may be installed in the connections from the street mains.

This makes sense, but unfortunately another section states: 13114.5 The governing body of any city or county may enact ordinances or laws imposing restrictions greater than those imposed by Sections 13113 and 13114. (Added by Stats. 1955, Ch. 1480.) AND many water purveyors, who are not city or county officials simply ignore the law. If you want to use their water, you abide by their demands! No single user wants to take the effort to fight. This can be really expensive, especially when a backflow is imposed on an existing system. The added friction loss can mean the whole system has to be recalculated, and often piping upgraded.

I would like to see the industry help to pass laws to eliminate backflows if they are not accomplishing anything.

Please share any ideas of who and how to help, or any examples if there are actual health issues. Thanks.

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7 Comments

Dan Wilder

6/3/2026 08:34:53 am

Several...the individual responsibility and costs compared to the public health and infrastructure costs to remediate issues make your argument difficult...May not have been an issue in the past when large fires and large water demands were limited but growth and what is burning has likely brought up some issues with the status quo. Also, this would be an AWWA & Cross Connect issue to be changed.

Doing a little research into the molecular makeup or dissolved iron in water vs iron supplements took me down a road of OChem I'd rather not try but in summary, they are different compounds and unrelatable in this context.

https://www.epa.gov/system/files/documents/2021-12/ds-toolbox-fact-sheets_ccc.pdf

https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/docs/2025/fire-sprinkler-memo-09172025.pdf

https://assets.noviams.com/novi-file-uploads/rwau/Training/Cross_Connection_Control_Program/Resources/case_history-xconn-890f8aff.pdf

https://backflow.club/wp-content/uploads/2024/09/Backflow-Assembly-Failure-Incidents-v1.pdf

https://www.amwater.com/paaw/Resources/PDF/Backflow%20incidents%20that%20could%20have%20been%20prevented.pdf

Frank P Savino link

6/3/2026 08:38:26 am

City water presuure fluctuates depending on time of day and other factors. For example, at 7:00 in the morning when everyone is taking a shower, the system wide water pressure, inculding the pressure in a building sprinkler system goes down. In the middle of the night, when everyone is sleeping, the pressure goes up. These pressure fluctuations cause water to flow into and out of the sprinkler system. If the sprinkler system has antifreeze, which is very toxic, that antifreze will get into the drinking water. In addition, there are cutting oils and a wide range of bacteria that develop and grow in stagnent sprinkler systems which are toxic. Therefore, sprinkler system water should be kept out of the public water drinking supply. It is the plumbing code that governs all of this. That is where you need to look, not in NFPA 13.

Anthony

6/3/2026 08:44:19 am

Cross contamination is a serious health threat and should be taken extremely seriously. I would fight to keep the codes in place now as they are or make them more stringent.

The laws are not confusing, provide a cross contamination prevention device to prevent potable water mixing with sprinkler water.

If you think sprinkler water is healthy to drink please open up a test drain and take a sip. That water has been mingling with cutting oils, paint, dope, lead, lubricants and usually 25 years of microbial growth and degenerated steel pipe lining. This doesn't even touch on tank systems which are not regulated for microbial growth. In no way do you want water that has been sitting stagnate for years being allowed to mix with

Talk to any plumber about the dangers of dead legs in a plumbing system and you'll get an ear full about metal leaching and bacterial growth. This is the same idea but on a massive scale.

anthony

6/3/2026 08:54:34 am

I hate to get on my high horse early in the morning...

Just because a solution is old or mandated everywhere doesn't mean it doesn't work or isn't needed. Like the fools who are against pasteurizing milk and never saw a dairy farm or smelled one.

Back flow preventers and RPZs are amazing tools that keep communities safe they are incredibly cheap compared to the cost of remediation. Going backwards away from good sanitation in the pursuit of .00001% of a building cost is the worst type of policy imaginable. Next we'll hear that we shouldn't have smoke alarms because everyone knows they only go off when you burn a roast in the the oven.

Ricardo Gonzales

6/3/2026 08:51:30 am

No code or AWWA reference, but have you ever had the displeasure of getting wet by a sprinkler system that had been sitting for a few months much less years? Unfortunately, I have, the water wreaks of sewer and that is my opinion from a sprinkler break 5 days after installation and 2 months after installation. Both instances I was inspecting the buildings when the breaks occurred. The cleanup was not inexpensive in either case.
Denver Water considers sprinkler water a contaminant and mandated all sprinkler systems be fitted with a AWWA certified backflow preventer. While working for the Denver Fire Department, we probably saw several hundred buildings installing them for the 1st time and about that many upgrading. It's worth checking with your local Water Supplier.

David Kendrick

6/3/2026 10:07:29 am

During my apprenticeship and early years as a journeyman, we typically installed a riser with a swing check, followed by an alarm valve, dry pipe valve, deluge valve, or preaction valve. Functionally, that meant a single check valve—or, in the case of an alarm valve, effectively two check valves in series. This was the majority of the installs I worked on in my youth. Fire pumps, above ground tanks, open water supplies usually involved engineering that outlined details to protect the water supply.

If these components were serviced and inspected in accordance with NFPA 13A, (I’m that old) the check valve function would have been verified.
In practice, that often did not happen. Failures and documented backflow incidents did occur.

Then comes the Federal Clean Water Act. When this law was being crafted testimony and documented cases pointed to backsiphonage, cross connection and backpressure problems caused by equipment failure, also untrained or poorly informed workers.

The Federal response was to require additional devices. These are usually at the customer’s expense, intended to reduce the likelihood that equipment failure and untrained or ill-informed workers would create problems. Whether that approach has been effective remains open to debate.

Keep in mind Water purveyors are generally responsible for supplying potable water up to the point of connection with the customer, and their role includes protecting the integrity of that supply. Given that responsibility, it is difficult to move away from a model that has been in place for more than 40 years.

At the same time, the original causes of backflow concerns still remain—particularly the risk of errors created by untrained or inadequately informed workers.

Training, third party certification of that training and requiring trained workers to perform work and inspections was one of the major issues causing backflow requirements and is still an issue for many jurisdictions.

Stepping down from my soapbox.

William Heruberger

6/5/2026 06:43:20 am

Not to be picky but a Backflow is not used to prevent backflow. Backflow is what occurs when water backflows into the potable water supply.

Now onto the original question.
.
The 2024 International Fire Code

912.6 Backflow protection.

The potable water supply to automatic sprinkler and standpipe systems shall be protected against backflow as required by the International Plumbing Code .

The 2024 International Plumbing Code where we generally find the required backflow protection on a fire sprinkler system.

608.17.4 Connections to automatic fire sprinkler systems and standpipe systems.
The potable water supply to automatic fire sprinkler and standpipe systems shall be protected against backflow by a double check backflow prevention assembly, a double check fire protection backflow prevention assembly or a reduced pressure principle fire protection backflow prevention assembly.

The Uniform Plumbing Code is almost identical.

A Health Hazard for Systems without Backflows?

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