Filed initially with the Secretary of State on April 4, 1972, under Act 98, P.A. 1913, these rules took effect 15 days after filing. On January II, 1978, these rules were adopted by reference into the Administrative Rules under Act 399, P.A. 1976, which is the Michigan Safe Drinking Water Act.

(By authority conferred on the department of public health by Act 399, P.A. 1976, and by sections 6, 10, of Act No. 98 of the Public Acts of 1913, as amended, and sections 9 and 427 of Act No. 380 of the Public Acts of 1965, as amended, being sections 325.203, 325.206, 325.210, 16.109, and 16.527 of the Compiled Laws of 1948.) R 325.11401 Definitions

Rule 1401. As used in this part:

(a) "Backflow" means water of questionable quality, wastes, or other contaminants entering a public water supply system due to a reversal of flow.

(b) "Cross connection means a connection or arrangement of piping or appurtenances through which a backflow could occur.

(c) "Safe air gap" means the minimum distance of a water inlet or opening above the maximum high water level or overflow rim in a fixture, device, or container to which public water is furnished which shall be at least 2 times the inside diameter of the water inlet pipe, but shall not be less than 1 inch and need not be more than 12 inches.

(d) "Secondary water supply" means a water supply system maintained in addition to a municipal type public water supply, including but not limited to water systems from ground or surface sources not meeting the requirements of Act No. 98 of the Public Acts of 1913, as amended, being sections 325.201 to 325.214 of the Compiled Laws of 1948, or water from a public water supply which in any way has been treated, processed, or exposed to any possible contaminant or stored in other than an approved storage facility.

(e) "Submerged inlet" means a water pipe or extension thereto from a public water supply terminating in a tank, vessel, fixture, or appliance which may contain water of questionable quality, waste, or other contaminant and which is unprotected against backflow.

(f) "Water utility" means a governmental unit, municipal or private corporation, association, partnership, or individual engaged in furnishing water to the public for household or drinking purposes.

R 325.11402 Compliance with regulations and local codes.

Rule 1402. A connection with a public water supply system shall comply with existing laws, ordinances and rules including:

(a) Act No. 266 of the Public Acts of 1929, as amended, being sections

338.901 to 338.917 of the Michigan Compiled Laws.

(b) Local ordinances or rules providing acceptable protection against cross connections.

R 325.11403 Cross connections prohibited.

Rule 1403.

(1) A cross connection shall not be made between a public water supply system and a secondary water supply.

(2) A cross connection shall not be made by submerged inlet.

(3) A cross connection shall not be made between a public water supply and piping which may contain sanitary waste or a chemical contaminant.

(4) A cross connection shall not be made between a public water supply system and piping immersed in a tank or vessel which may contain a contaminant.

R 325.11404 Local cross connection control programs.

Rule 1404.

 (1) A water utility shall develop a comprehensive control program for the elimination and prevention of all cross connections. The plan for the program shall be submitted to the department of public health for review and approval within one year after the effective date of these rules. when the plan is approved, the water supply shall implement the program for removal of all existing cross connections and prevention of all future cross connections.

(2) The program shall include but not be limited to:

(a) A complete description of the method of administering the program, including the designation of inspection and enforcement agency or agencies. The local authority for implementation of the program shall be indicated, preferably by ordinance.

(b) A time schedule for inspection and reinspection of all water utility customers premises for possible cross connections. The periodic reinspection shall be used to ascertain whether or not safe air gaps or required protective devices are in place and in working order.

(c) A description of the methods and devices (as approved by the department of public health) used to protect the public water supply.

R 325.11405 Corrections and protective devices.

Rule 1405.

(1) A user of public water shall obtain written approval by the water utility or authorized inspection agency of any proposed corrective action or protective device before using or installing it.

(2) The total time allowed for completion of the necessary corrections shall be contingent upon the degree of hazard involved and include the time required to"obtain and install equipment. If the cross connection has not been removed, after a reasonable period of time, the water utility shall physically separate the public water supply from the on-site piping system in such a manner that the two systems cannot again be connected by any unauthorized person.

(3) A water utility shall report annually to the department of public health on the status of the cross connection control program on a form provided by the department.

R 325.11406 Piping identification.

Rule 1406. When a secondary water source is used in addition to a public water supply system, exposed public water and secondary water piping shall be identified by distinguishing colors or tags and so maintained that each pipe by be traced readily in its entirety. If piping is so installed that it is impossible to trace it in its entirety, it will be necessary to protect the public water supply at the service connection in a manner acceptable to the department of public health.

R 325.11407 Private water storage tanks.

Rule 1407. A private water storage tank supplied from a public water supply system shall be deemed a secondary water supply unless it is designed and approved for potable water usage.

The following section outlines the various devices used for protection against cross connections. Specific installations and/or use restrictions apply to some of these devices or methods of protection. Some methods noted are not approved, but nevertheless have been used in the past as a means of protection.

14.3.1 Air Gap Separation

"Safe air gap" is defined in Rule 325.11401 as, "the minimum distance of a water inlet or opening above the maximum high water level or overflow rim in a fixture, device, or container to which public water is furnished which shall be at least two times the inside diameter of the water inlet pipe, but shall not be less than one inch and need not be more than 12 inches." The illustrations on Page 10 show safe air gap arrangements for water storage and makeup tanks.

The installation shown on Page 11 of an approved air gap at the service line (entrance to plant system) is an acceptable solution for protecting the public system from cross connections. Any installation must be properly designed as no bypass will be allowed. With an air gap, this would necessitate standby pumps and power if a continuous supply of water is required.

Air gaps used as routine protection in homes for installations such as sinks, bathtubs, washers, and water softeners have certainly proven to be an effective method of protecting against backsiphonage.

However, for other users and other types of cross connections, an air gap on the interior portion of the system is not generally accepted as satisfactory protection. Theoretically, it is a fine solution, however, practically speaking, air gaps on inplant problems have proven to be unacceptable, particularly where pressure is required or where splashing cannot be or is not tolerated. Examples of such installations would be hospital and pathology laboratories, mortuary tables and sinks, research (bacteriologic and/or chemical) laboratories, plating tanks, and wash and rinse tanks.

An air gap installed on the customer's service line is theoretically the highest type of protection for the public water supply system. However, it must be properly designed to provide a constant supply of water at an acceptable pressure. A properly designed and approved air gap installed at the service line will satisfactorily protect the public water supply system from the possibility of backflow from all types of cross connections.

LARGE BUILDING WITH AIR GAP AT WATER STORAGE TANK

AIR GAP AT MAKEUP TANK FOR A DUAL WATER SYSTEM

'SAFE AIR GAP' - GROUND LEVEL STORAGE TANK

14.3.2 Reduced Pressure Principle Backflow Preventers

The reduced pressure principle backflow preventer is an arrangement of spring loaded check valves designed to prevent the backflow of water. Page 13 illustrates a cross section of the device. Zone 1 within the schematic diagram of the reduced pressure principle backflow preventer is maintained at the same pressure as the public water supply system. During normal operating conditions as shown on Page 14 the water will pass the spring loaded check valve "A" into zone 2. The zone of highest pressure is shown as the darkest shaded area, and the pressure decreases as the intensity of the shading decreases. The pressure within this zone is less due to the head loss passing through check valve "A". The water then passes through the spring loaded check valve ~B" into zone 3 and on to the inplant system with pressure again reduced. The spring loaded differential pressure relief valve "C~ is maintained in a closed position due to the higher pressure in zone I than in zone 2. The spring loaded pressure of approximately 2 psi tends to hold the relief valve in an open position.

If the pressure within the public water supply system becomes less than the inplant system (Page 15), the normal direction of flow through the backflow preventer would tend to reverse. However, check valve "B" should seat and restrict the flow of any water back even as the higher pressure from the inplant system would enter zone 2, but check valve "A" would restrict further movement back toward the public water supply system.

Valve "C" at the differential pressure relief port is normally held in a closed position since the pressure in zone I is higher than in zone 2. The pressure differential opposes a 2 psi residual pressure on the spring loaded relief valve. Thus, if the water pressure in zone 2 plus the 2 psi residual spring loaded pressure on the relief valve is greater than the pressure in zone 1, the differential pressure relief valve. "C" opens and water is discharged through the relief port to the atmosphere. There must be a free discharge at the drain port and the discharge must be visible. If it is necessary to pipe any discharge to another area, it may be accomplished by a free discharge through a visible air gap into a collection device such as a funnel and gravity flow to discharge at a more desirable point.

The water utility and any user contemplating the installation of this unit must understand that it operates on the basis of a pressure loss across each of the valves. If the user cannot obtain satisfactory service due to the built-in head loss, problems can be anticipated if such a device is installed.

Depending upon the design of the internal piping system, it may be possible to isolate certain critical areas with such a device; an example would be a bay of plating tanks, particularly if fed by only one service line.

REDUCED PRESSURE PRINCIPLE BACKFLOW PREVENTER

This device when properly installed, tested, and maintained will be acceptable for protection of the public water system from backflow in the situations listed in Section 14.8. Since the device has a drain port between the two spring loaded check valves, the reduced pressure principle backflow preventer must be installed in a location not subject to flooding and also where accessible for observation. It also must be protected from adverse weather conditions as the diaphragm which is a part of relief valve "C" could be damaged by freezing. Care must be taken to install these devices in accordance with manufacturers recommendations.

Maintenance is necessary for any mechanical equipment if we are to rely upon it maintaining its protective functions; therefore, any mechanical protective device must be installed in a location where it is accessible for routine inspection, testing, and required repair. These devices are mechanical in nature and subject to breakdown, and they must be isolated during periods of inspection and repair. If there is only one service line from the public system and if water service is required 100% of the time, it will be necessary to install a second reduced pressure principle backflow preventer in parallel with proper valving in order to provide for an uninterrupted protected supply from the public system.

The reduced pressure principle backflow preventer by itself when properly installed and maintained will provide adequate protection for the public water supply system from all types of cross connections that may result in either backpressure or backsiphonage backflow. Page 17 illustrates a typical reduced pressure principle backflow preventer.

14.3.3 Four-Way Plug Valve

When an internal plumbing system is supplied by both a secondary water supply and a public water supply system, an effort must be made to separate the two sources. When properly installed, the four-way plug valve as shown on Page 18 provides air gap separation since one of the two sources is vented to the atmosphere. This prevents a secondary source from continually being pumped against the public supply. The four-way plug valve should be installed in such a manner that the line vented to the atmosphere will drain. The four-way plug valve has considerable head loss built in, however, unlike the reduced pressure principle backflow preventer, this head loss can be reduced by oversizing the device. It is not satisfactory protection if the downstream piping within the customers premise is further cross connected.

14.3.4 Four-Way Plug Valve and Reduced Pressure Principle Backflow Preventer in Series

Page 19 illustrates the relative locations of the two pieces of equipment when the four-way plug valve and a reduced pressure principle backflow preventer are installed in series. This combination of protective devices is meaningful if the entire secondary water supply and the public water supply come together at one point only and neither source bypasses the four-way plug valve. While the two pieces of equipment installed in series provide the recommended solution to these problems, it may be acceptable to utilize the reduced pressure principle backflow preventer by itself with most secondary water supplies. The local program should define acceptable protection for certain situations since some communities may well require the installation of the two devices in series.

14.3.5 Vacuum Breakers

Vacuum breakers may be acceptable for some applications, however, they should not be solely relied on to protect the public water supply from backsiphonage at customers such as medical laboratories, pathology laboratories, bacteriologic, physiologic, and chemical research laboratories, hospitals, plating industries, etc.

Vacuum breakers are effective against backsiphonage only and shall not be used where there is any possibility that positive pressure either from a pump, a pressure device, or from elevated piping on the discharge side can be developed on the downstream side of the device or where it may be subject to flooding.

Properly installed vacuum breakers will provide adequate protection for individual toilets, urinals, high school chemistry laboratory sinks, and lawn sprinkling systems. The vacuum breakers installed to protect against backsiphonage on lawn sprinkling systems must be full sized (pipe size) and must be at least 14 inches above ground level and at least 6 inches above the highest sprinkling head (12 inches if using a pressure vacuum breaker). On large lawn sprinkler systems and distribution lines serving them, it may be acceptable to install two or more vacuum breakers in parallel. Paqes 21 through 24 illustrate both atmospheric and pressure type vacuum breakers and typical applications.

he hose bibb type atmospheric vacuum breaker shown on Pane 22 when installed on a frost proof outlet typically will not allow drainage to occur. Consequently, the vacuum breaker must be manually opened to prevent ice damage to the hose outlet piping.

14.3.5.1 Atmospheric Vacuum Breaker

This device allows air to enter the water supply line when the pressure in the public system or the service line is reduced to zero or below. It must be installed on the discharge side of the last shut-off valve in order that the float mechanism will be operated routinely, hence not "frozen in an open position. This device must be installed in the high point of the water supply piping at least 6 inches above the piping outlet. An atmospheric vacuum breaker should not be under continuous pressure for more than 12 hours.

VACUUM BREAKER CROSS-SECTION

(Shown Open to Atmosphere)

VACUUM BREAKER CROSS-SECTION

(Shown Open to Atmosphere)

TYPICAL INSTALLATIONS OF ATMOSPHERIC VACUUM BREAKERS

Sprinkler System Application

A. 14" Minimum recommended height above grade level

B. Vacuum breakers - Minimum of 6" above highest sprinkler head

C. Shut off valve must be upstream from atmospheric vacuum breakers

D. Two or more vacuum breakers in parallel may be required on large lawn sprinkler services to provide the rated flow of the service line.

Hose Bibb Application

Hose Bibb

Vacuum Breaker - Must be installed at least 6" above ground

14.3.5.2 Pressure Vacuum Breaker

This device has a vacuum relief valve which is internally loaded, normally by means of a spring. Because of this spring loading, the pressure vacuum breaker can be installed in a location where it is continuously under normal pressure; i.e., on the supply side of a shut-off valve. It must be installed in the high point of the water supply piping at least 12 inches above the piping outlet.

A. Valves may be located downstream from pessure vacuum breakers

B. This unit is not positive protection against back pressure

Test Cocks

Vacuum Breaker Cross-Section (Shown Open to Atmosphere)

INSTALLATION OF VACUUM BREAKERS ON PROCESS TANKS

(Prohibited in some jurisdictions)

Atmospheric Vacuum Breaker - No Valves Allowed Downstream from Atmospheric Vacuum Breakers

Pressure Vacuum Breaker - Valves May Be Installed Downstream from Pressure Vacuum Breakers

NOTES:

1) Vacuum breakers should not be used in a dusty or corrosive atmosphere

2) Use hot water type vacuum breakers on hot water lines

3) If vacuum breakers are used as protection on tanks containing liquids which are hazardous to health, further protection should be required on the main service line

14.3.6 Barometric Loop

The barometric loop as shown on Page 27 can be installed to adequately protect the city supply from backsiphonage. The device must be properly designed, must be installed so that it is adequately protected against freezing, and must not be used in a position where it could possibly be subject to backpressure. Air lift is a potential problem and a check valve should be installed at top of loop to break any possible flow.

When properly installed, the barometric loop will protect the public water supply system from backsiphonage. The top leg of the loop must be a minimum of 35 feet above the spill rim of the highest free water surface, as a perfect vacuum can lift water approximately 34 feet

14.3.7 Unapproved Methods

The following is a brief discussion of methods which are not approved to protect against backflow.

14.3.7.1 Check valves, Double check valves

Check valves even when installed in series have not proven to be effective protection against the hazards of backflow. These devices will not be acceptable for providing essential health protection to the public water supply system. They may be used to protect the public supply from aesthetic problems such as stale water in privately owned storage tanks maintained for fire protection. Double check valve assemblies are acceptable means of protection for low pressure untreated boilers.

A device that is many times mistaken for a reduced pressure zone backflow preventer but which is considered only equivalent to a double check valve arrangement is the vented double check backflow preventer. This device is acceptable only for low hazard applications where double checks or double check valve assemblies are permissible. These devices are listed in the appendix with the double check valve assemblies.

14.3.7.2 Spool connection

This type of protection against cross connections as shown on Page 28 has in the past been used to separate the public supply. from a secondary supply. This type of separation is not an acceptable form of protection and should be replaced by an approved device. If an industry, etc., wishes to maintain a spool connection, it could be allowed with a reduced pressure principle backflow preventer installed on the public water supply side of the spool connection. The reduced pressure principle backflow preventer should be installed as soon as possible following the discovery of the spool connection.

Basically, no credit for protection can be given to a spool connection and these existing units should be replaced as deemed necessary by the potential hazard involved and details of the local enforcement program.

14.3.7.3 Swing connection

The type of protection against cross connections as shown on Page 28 has in the past also been used to separate the public supply from a secondary supply. This type of device can be acceptable from a public health standpoint only if a reduced pressure principle backflow preventer is installed on the public water supply side of the connection. It should be noted that this type of device is difficult and cumbersome to use and is a detriment to its real usefulness.