1 
 Outline of the Revision:  
(Changed portions are underlined  in below tables)  
 (1)  The standard for pressure resistance and the pressure resistance performance test (Ministerial Ordinance 
Article 1, paragraph (1); Public Notice No. 1)  
Proposed revision  Prese nt provision  
A.  The pressure device with a structure that has no 
connection with water without running through the 
pressure reducing valve and its downstream section 
in the water supply equipment in which the water 
supply pipe and the water supply equipm ent etc. 
attached to it function in an integral structure, which 
is equipped with a pressure reducing valve and a 
pressure device on its downstream side : 
 … No water leakage, deformation, breakage, or 
other problems shall occur when a hydrostatic 
pressure at the maximum discharge pressure of 
the pressure device  is applied for one minute.  
 
B.  The section where the outer wall of  the water pipe 
(inside the heat exchanger) for water in the bath tub 
and water , such as supplied hot water , are in contact 
with eac h other in the water supply equipment  in 
which the water supply pipe and the water supply 
equipment etc. attached to it function in an integral 
structure, which is equipped with a pressure 
reducing valve and has a structure that uses the heat 
exchanger  for both heating water in the bath tub and 
supplying hot water:  
 … shall have no joint, and no water leakage, 
deformation, breakage, or  other problems shall 
occur when a hydrostatic pressure of 1.75 MPa is 
applied for one minute.  A.  Storage -type water heater s and water supply 
equipment installed on their downstream side : 
  
 
 
 
 
 
… No water leakage, deformation, breakage, or 
other problems shall occur when a hydrostatic 
pressure of 0.3 MPa  is applied for one minute.  
 
 
B.  The water pipe (inside the heat exchang er) section 
for heating water in the bath tub in a storage -type 
water heater with a single tank and double water 
pipes : 
  
 
 
 
 
 
… shall have no joint, and no water leakage, 
deformation, breakage, or other problems shall 
occur when a hydrostatic pressure of 1.75 MPa is 
applied for one minute.  
 
 
 
 
 
 
 
 
  
2 
  (2)  The s tandard for backflow prevention and test in relation to destruction b y vacuum pressure (Mi nisterial 
Ordinance Article 5, paragraph (1) and Public Notice No. 5)  
Proposed revision  Present provision  
A.  For water supply equipment containing an 
atmospheric -type vacuum breaker  
(1) Water supply equipment containing a vacuum 
breaker:  
… The rise in the water level inside the transparent 
tube connected to the water supply equipment shall 
not exceed half of the vertical distance from t he 
position where the backflow prevention function 
works  to the water surface of the water receiver . 
(2) Other atmospheric -type vacuum breakers:  
… The rise in the water level inside the transparent 
tube connected to the water sup ply equipment shall 
not exceed half of the vertical distance from the 
bottom of the joint between the tube connected to 
the intake port and the inflow tube, or the bottom of 
the intake port, whichever is lower , to the water 
surface . 
  when a pressure of -54 kPa is applied from the inflow 
side. 
 
B.  Water supply systems having a spout with a nominal 
diameter of 25 mm or below shall secure the specified 
horizontal distance from the adjacent wall to the center 
of the spout , and the  specified vertical distance from the 
overflow surface to the bottom of the spout  accordi ng to 
the classification of the nominal diameters listed in the 
Ministerial Ordinance Appendix 2.  
 
C.  For the test of a vacuum breaker or a 
decompression -type backflow preventer, the test 
equipme nt shall be installed in the following manner:  
 (1) V acuum breaker:  
… The vertical distance from the lower edge of the 
vacuum breaker or the position where the 
backflow prevention function works to the water 
surface  is 150 mm.  
 (2) Decompression -type backf low preventer:  
  … The vertical distance from the lower edge of the A.  For water supply equipment containing an 
atmospheric -type vacuum breake r, the rise in the water 
level inside the transparent tube connected  to the water 
supply equipment shall not exceed half of the vertical 
distance from the air suction sheet surface of the 
atmospheric -type vacuum breaker  to the water surface of 
the water receiver  when a pressure of -54 kPa is applied 
from the inflow side.  
 
 
 
 
 
 
 
 
 
 
 
 
B.  Water supply systems having a spout with a nominal 
diameter of 25 mm or below shall secure the specified 
horizontal distance from the adjacent wall to the center of 
the spout , and the specified vertical distance from the 
overflow surface to the center of the spout  according to 
the classification of the nominal diameter s listed in the 
Ministerial Ordinance Appendix 2.  
 
C.  For the test of a vacuum breaker or a 
decompression -type backflow preventer, the test 
equip ment shall be installed in a ma nner that the vertical 
distance from the air suction sheet surface to the water 
surface  is 150 mm.  
 
 
 
 
  
3 
 relief valve drain of the decompression -type 
backflow preventer to the water surface  is 150 mm.  
 
D.  For water supply equipment containing an 
atmospheric -type vacuum breaker, the overflow port 
inside the water receiver of the test equipment shall be 
raised and the water receiver shall be filled with water up 
to the specified test water level. Then, the same 
operation as that of the vacuum break er and the 
decompression -type backflow prevente r shall be 
performed with the water stopping mechanism of the 
test equipment both fully open and closed . 
 
E.  Example of test system for destruction by vacuum 
pressure  
 
 
 
F.  Example of test syste m for destruction by vacuum 
pressure in relation to water supply equipment with an 
integral spout  
 
 
  
 
 
D.  For water supply equipment containing an 
atmospheric -type vacuum breaker, the overflow port 
inside the water receiver of the test equipment shall  be 
raised and the water receiver shall be filled with water up 
to the specified test water level. Then, the same operation 
as that of the vacuum breaker and the 
decompression -type backflow preventer shall be 
performed with the water stopping mechanism of the test 
equipment fully open . 
 
E.  Example of test system for destruction by vacuum 
pressure  
 
 
F.  Example of test system for destruction by vacuum 
pressure in relation to water supply equipment with an 
integral spout  
 
 
 V acuum 
system V acuum 
gauge Within 1 m  
Needle valve  T est 
equipment 
Transparent 
tube 
Base V acuum 
suction On-off valve 
W ater 
container V acuum 
tank V acuum 
gauge Within 1 m  
Needle valve  T est 
equipment 
Transparent 
tube 
Base V acuum 
pump 
On-off valve 
W ater 
container V acuum 
gauge 
V acuum 
system V acuum 
gauge 
Needle valve  
V acuum 
suction On-off valve 
Joint 
Spout  Within 1 m  
Overflow 
pipe T est water level  
W ater 
receiver Test 
equipment V acuum 
gauge 
V acuum 
tank V acuum pomp  
Needle valve  V acuum 
gauge 
V acuum suction  
Joint 
Spout  
Overflow pipe  W ater 
receiver T est water level  
T est 
equipment