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Where back pressure is possible Only allowed where no back pressure is possible
(any hazard) (low hazard only) (low hazard only) (control valve may be down-
stream of device)
(no control valve down-
stream of device)
(no control valve down-
stream of device)
A. Boiler, other than one- or two-family residential X
B. Boiler, one- or two-family residential X X
C. Car wash X X X
D. Carbonated beverage machine (postmix) (see part 4715.2163) X
E. Chemical line X
F. Chemical tank X X X
G. Chiller X
H. Cooling tower X X X
I. Dental units (separate assembly required for each unit)2 X
J. Dishwasher, commercial X X
K. Fire sprinkler system3 X X
L. Flush tank (water closet, urinal, similar) (see part 4715.2150) X X X
M. Flush valve (water closet, urinal, similar) (see part 4715.2150) X X X
N. Food and beverage equipment or system X X X X X
O. Garbage can washer X X X
P. Glycol or other antifreeze system X
Q. Lab equipment X X X
R. Lab faucet X
S. Laundry machine, commercial X X X
T. Lawn, garden, or greenhouse sprinkler system X X X
U. Operating, dissection, embalming, or mortuary table (see part 4715.1950) X X X
V. Private potable water supply (where permitted by administrative authority) X X X
W. Private nonpotable water supply (where permitted by administrative authority) X
X. Process line X
Y. Process tank X X X
Z. RV dump station X X X
AA. Sewage treatment X X X
BB. Soap dispenser (see part 4715.2165) X X X
CC. Swimming pool, fountain, pond, baptistry, aquarium or similar X X X
DD. Threaded hose connections, including: hose bibbs, hydrants, service sinks, laundry trays X X X4
EE. Truck fill X X X
FF. Vacuum systems or aspirators X X X

1. For installations not listed in this part, review with the Administrative Authority.

2. If a dental water treatment system that has been cleared by the Food and Drug Administration (FDA) for marketing is to be installed, a single RPZ device shall be installed upstream of the dental water treatment system and not required on each branch line. The system shall be installed and maintained according to the treatment system manufacturer's instructions. Water lines of less than one-half inch are permitted downstream of the water treatment system when required by the manufacturer.

3. Installations must comply with AWWA-M14, chapter 6 (1990) except that the following statement is deleted from section 6.3: At any time where the fire sprinkler piping is not an acceptable potable water system material, there shall be a backflow-prevention assembly isolating the fire sprinkler system from the potable water system.

4. A vacuum breaker installed as an integral part of a product approved to a standard does not require additional backflow prevention on the hose threads; the product must be constructed so that if the integral backflow preventer is removed, the remaining threads will not be hose thread type. An unprotected threaded hose connection must be protected against backflow by addition of a backflow preventer complying with ASSE 1052.

Statutory Authority:

MS s 16B.59 to 16B.75; 326.37 to 326.45; 326B.101 to 326B.194; 326B.43 to 326B.49; 326B.52


15 SR 76; 19 SR 590; 23 SR 686; 28 SR 146; L 2007 c 140 art 4 s 61; art 6 s 15; art 13 s 4; L 2008 c 337 s 64; 36 SR 1479

Published Electronically:

November 13, 2012

700 State Office Building, 100 Rev. Dr. Martin Luther King Jr. Blvd., St. Paul, MN 55155 ♦ Phone: (651) 296-2868 ♦ TTY: 1-800-627-3529 ♦ Fax: (651) 296-0569