The most often asked question about backflow protection is also the title of this article, “How do we decide the proper cross-connection protection?” The selection of the required method, device, or assembly is determined by a number of factors. To start, we need to understand that any connection presents a hazard. We have two levels, or degrees, of hazards — each and every connection is either a high or low hazard. It is a binary choice we need to make. This choice is also the most important one we make. A high hazard presents a danger to the life and health of individuals. A low hazard will simply affect the aesthetic quality of the water. If a backflow event occurs, a low hazard threat may discolor the liquid and have a foul taste and/or smell. If consumed, the water will not affect the health of the individuals drinking or preparing food with it.
A list of high hazard facilities and threats includes, but is not limited to, the following: sewage, industrial wastewater treatment plants, and pumping stations; paper manufacturing and processing, dye plants, petroleum processing and storage, printing plants, chemical manufacturing and processing, industrial fluid systems, steam generation, rubber processing, and tanneries; canneries, breweries, food processing, detergent processing, milk processing, ice manufacturing, meat packing, and poultry processing; hospitals, clinics, laboratories, veterinary hospitals, mortuaries, and embalming facilities; shipyards, marinas, nuclear reactor facilities, and power generation facilities; metal-plating, photo processing, cleaning laundries, commercial car washes, commercial refrigeration systems, and dry-cleaning establishments; irrigation systems for commercial greenhouses, and spraying and irrigation systems using weedicides, herbicides, and exterminators; boiler systems, cooling towers, and internal fire-fighting systems using conditioners, inhibitors, and foam.
After the degree of hazard is found, we must determine what type of backflow may result from the potential hydraulic conditions within the system. Do I need to consider backpressure or backsiphonage protection? Or are both possible? Are we looking at a direct or an indirect cross-connection? The answer to these questions will be vital in making the correct decision. Let us look at some actual situations, work the problem, and find the answer.
In a sewage treatment facility, the number of hazards from internal cross-connection to the potable water system will be a serious issue. This is definitely a high hazard situation that must be addressed. We would start with the service connection to the facility. A reduced pressure principle assembly will need to be installed as containment protection. Within the facility, we would need to look at all potable water piping, outlets, fixtures, and any drainage fittings related to the water system. This would include heating and cooling equipment, fire protection systems, and the process piping used in the chemical treatment of waste and sewage entering the plant.
Cross-connection protection at sewage treatment plants has two goals in mind: the first is protecting the public water system from contamination. The second is to protect the plant workers and the plant itself from any contamination related to water quality. This type of facility uses water in many different ways, including water for fire protection, process use, and irrigation. It could also include recycled or reclaimed water systems. We must protect potable water from reclaimed water as if the reclaimed water were sewage – then, the reclaimed water should be protected as if the reclaimed water were potable water.
Odor control systems are common in treatment plants and may use water in their process. Odor control involves sewage aerosols and particulates. Water supplied to odor control equipment, or to hose bibs in the odor control area, should be considered in direct contact with sewage. Water supplied to odor control areas and equipment must utilize an air gap. Within this type of facility, high hazard protection will be the most common type used and will include reduced pressure principle assemblies. It will also include vacuum breakers – both pressure and atmospheric type. As with any cross-connection, each must be looked at individually as a unique connection. The protection needed may be as simple as a hose bibb vacuum breaker or as complicated as a reduced pressure principle assembly.
In facilities with multiple pressurized systems, labeling of the piping is required. The 2021 Uniform Plumbing Code® (UPC) spells this out in Section 601.3 Identification of a Potable and Nonpotable Water System. In buildings where potable water and nonpotable water systems are installed, each system shall be clearly identified in accordance with Section 601.3.1 – 3.5.
601.3.1 Potable Water. Green background with white lettering.
601.3.2 Color and Information. Each system shall be identified with a colored pipe or band, and coded with paints, wraps, and materials compatible with the piping. Except as required by Section 601.3.3, nonpotable water systems shall have a yellow background with black uppercase lettering, with the words “CAUTION: NONPOTABLE WATER, DO NOT DRINK.” Each nonpotable system shall be identified to designate the liquid being conveyed, and the direction of normal flow shall be clearly shown. The minimum size of the letters and length of the color field shall comply with Table 601.3.2. The background color and required information shall be indicated every twenty feet (6096 mm), but not less than once per room and shall be visible from the floor level.
601.3.3 Alternate Water Sources. Alternate water source systems shall have a purple (Pantone 512, 522C, or equivalent) background with uppercase lettering, and shall be field or factory marked as follows:
- Gray water systems shall be marked in accordance with this section with the words “CAUTION: NONPOTABLE GRAY WATER, DO NOT DRINK” in black letters.
- Reclaimed (recycled) water systems shall be marked in accordance with this section with the words: “CAUTION: NONPOTABLE RECLAIMED (RECYCLED) WATER, DO NOT DRINK” in black letters.
- On-site treated water systems shall be marked in accordance with this section with the words: “CAUTION: ON-SITE TREATED NONPOTABLE WATER, DO NOT DRINK” in black letters.
- Rainwater catchment systems shall be marked in accordance with this section with the words: “CAUTION: NONPOTABLE RAINWATER, DO NOT DRINK” in black letters.
601.3.4 Fixtures. Where vacuum breakers or backflow preventers are installed with fixtures listed in Chapter 17, identification of the discharge side shall be permitted to be omitted.
601.3.5 Outlets. Each outlet on the nonpotable water line that is used for special purposes shall be posted with black uppercase lettering as follows: “CAUTION: NONPOTABLE WATER, DO NOT DRINK.”
Labeling and identification of piping systems will help ensure that cross-connection control inspections are more accurate, and installers and inspectors are able to identify potential problems to either install the correct protection or eliminate cross-connection completely. As the joining methods and installation of piping and materials have become easier and less complicated, our systems have become more complicated. Labeling of systems is a critical part of any cross-connection program.
Let us look at modern hotels as another example of a common facility type that requires backflow protection. In a full-service hotel, we will have fire protection systems, plumbing fixtures, heating and cooling equipment, commercial laundry, restaurants, bar facilities, pools and spas, salons, irrigation systems … the list goes on. There will be cross-connections that must be addressed throughout these systems. Backsiphonage and backpressure issues will be present. We will be concerned about both high and low hazards in many areas of the facility. If we’re looking at the required protection, we need to look at each system type independently. The containment protection on this property will need to be a high hazard valve that protects against both backpressure and backsiphonage — a reduced pressure principle assembly will need to be installed. This installation will create a closed water system that will now require us to look at the possibility of thermal expansion.
Let’s start with the heating and cooling system. Does the type of heating or cooling system matter? The short answer is yes, it does. Many systems do not use water in their functionality. Many, however, do connect either directly or indirectly into the potable water supply, or into the aquafer. Those connected to water supplies must be looked at as potential or actual cross-connections, so a degree of hazard and an understanding of the type of backflow possible must be assigned. To do that, we need an understanding of how specific system use water and the basic hydraulic conditions that may be present.
The potential danger of this system has many variables. The first question to ask is whether the potable water is being connected to either the heating or cooling system. Water offers almost unlimited options for heating and cooling systems. Water systems enable solar systems, gas heating systems, and other renewable heating systems, as well as various cooling systems, to be combined and used together. Water is a highly effective heat transfer medium (heat transfer is the process whereby thermal energy or heat moves from one body or substance to another, and from hot to cold).
If water is being used, we must look at whether the water is being treated in any way. Why is chemical treatment needed? Although water is abundantly available for commercial use, it contains various minerals that create corrosion and scaling in heat exchangers. The process of scaling adversely affects heat transfer and can lead to equipment failure. Chemical treatment is required to prevent corrosion and scaling deposits. What chemicals are used in heating or cooling systems? Approved chemicals for water treatment may include Alkaline, Amines, Phosphates or Polymers, and Sulfites. The use of chemical treatment requires us to look at the proper cross-connection control much closer. A reduced pressure principle assembly or air-gap will be the required protection in these situations.
We will also need to look at the heating equipment for domestic hot water, including heaters and any storage tanks. We should also look at any recirculation systems present at the facility.
After the heating and cooling system is reviewed, the next stop on our list would be the kitchen and bar/restaurant areas. In commercial kitchens, we will find streamers, dishwashers, garbage disposals, prep sinks, floor sinks, floor drains, trap primers, ice machines, coffee makers, grease traps, glass washers, soda dispensing systems, and chemical dispensers — all tied directly or indirectly to the facility’s potable water systems. Each must be looked at individually as a unique connection. We need to understand the limits of the protection we are specifying or installing. Within this area, we may find a variety of protection used, ranging from physical air-gaps to atmospheric vacuum breakers to testable backflow protection assemblies. Even if protection is installed, it may have been incorrectly selected or, in some cases, simply installed wrong. It is very common to locate atmospheric vacuum breakers installed under continuous pressure or at a height below the fixture flood rim.
In the case of chemical dispensing equipment or other kitchen related equipment, it may have been installed after the facility was inspected and, as a result, was installed incorrectly. Cross-connection control is a process that never stops and requires continuous review to keep any facility in compliance.
The next piece of the hotel puzzle is to look at the fire protection system. Is the facility completely sprinklered? Is it a wet or dry system? Are there any antifreeze loops, fire pumps, or fire department connections? Is there auxiliary water available within 1,700 feet of the fire department connection? Have any additives been added to the water? Does the hotel have a standpipe system? What is the kitchen fire protection? All these questions (and more) must be answered before we know if the system will need to have a double check valve assembly or a reduced pressure principal assembly installed. Another question we’ll need to answer: does the local Authority Having Jurisdiction (AHJ) require the use of detector assemblies?
We will then need to look at the makeup water to any swimming pools or hot tubs. If a salon or spa is in place, we will need to review the steam room and/or sauna, along with fixtures and equipment like shampoo sinks or pedicure chairs. The fixtures in public restroom areas (and in the hotel rooms themselves) will also be a survey priority. If irrigation systems, fountains, or water gardens are incorporated into the facility, they will also need to be examined. Anything that is related to water use at the facility needs to be examined.
Whether we are looking at a single-family home or at a large hospital facility, we need to understand that each poses a hazard to our public water system. There is no one-size-fits-all solution that will allow us to protect both the public water system and the individuals in the facility itself. Cross-connection control is a never-ending, complicated process. We need to evaluate the hazard level of the facility and install point of service or containment protection to protect the public water system. We then need to install isolation or point of use protection within the facility to protect the individuals living or working in the facility. The job, however, is not completed when the building is occupied and has received its final inspection — the installed protection must be tested and maintained, and periodic surveys and inspections are needed on a regular basis to ensure system protection. The ASSE International motto says, “Prevention Rather Than Cure” — we need to take that suggestion and prevent problems before they can occur.
Article first published in Working Pressure magazine
Sean Cleary has been a member of United Association Local 524 Scranton, Pa. for more than 40 years. He has worked in all phases of the plumbing and mechanical industry, and is a licensed master plumber. Cleary is a past president of ASSE International and past chairman of the ASSE Cross-Connection Control Technical Committee. He is employed by IAPMO as the vice president of operations for the Backflow Prevention Institute (BPI).
Last modified: December 19, 2023