This document summarizes specifications and standards for water-saving closets in Japan. It provides an overview of global water usage standards for toilets, showing that Japan has led the way in setting a 5L standard. It then details Japan's changing standards over time as closets shifted to using less than 6L of water. The key requirements for water-saving closets are explained, including maintaining discharge, clean-up and transportation performance according to Japanese industrial standards. Test methods and pass criteria are described for evaluating these performance standards in Japan and other countries.

1. 1
Specifications & Standards
for Water-Saving Closets
1
Confidential
１．Overview
2
About Japanese Water-saving closets,
1.Explanation of the standards , specifications and
structures that realize the Water-saving
2.Explanation of the test methods and results for
transportation performance

2. 2
２．Global trends of Water-Saving
日本：5.0L
Progressive Global
Water-saving
UK:6.0L
Saudi
Arabia:6.0L
Singapore:4.5L
China:9.0L
urban areas:6L Japan:5.0L
Hong Kong:7.5L
(Sea water use)
USA:6.0L
Australia:6.0L
Brazil:6.0L
USA
Partially
regulated in 4.8L
Canada:6.0L
Mexico:6.0L
3
３．Change of Water-Saving closet (in case of Japan)
６Ｌ
８Ｌ
１０Ｌ
１３Ｌ
１６Ｌ
Numberofshipments(thousands)
※Quoted from the document of Japan Sanitary Equipment Association
Closets less than 6L
have become major
after 2008
Stead Growth of Water-saving closets in Japan!
Estimation of the water closets shipments of every flushing volume
year
4

3. 3
Requirements to realize water-saving
■ Water-saving with no reduction of performance of discharge , clean-up ,
transportation.(Observance of the Japanese Industrial Standard)
4.Realization of coexistence of clean-up ,
discharge , transportation performances
２
３
③ 洗浄性能
ボウル面の汚れを落とす能力
３
１
２
１
5
Discharge performance
(which means the ability of discharge
from toilet bowl to drainage line)
Clean-up performance
(which means the removal ability
against the wastes on bowl surface)
Transportation performance
(which means the ability to transport the
wastes through and clear the drain line
when flushed)
Indonesia
SNI0797-2006
-
①φ40Balls.density1.05
Test :5times
Discharge ≧4times
②Minimum φ36
wooden ball can pass
through the drain hole.
③Saw dust
≦5000mm2
④simulation materiaｌ
4pcs Test 10times
Discharge≧8times
⑤6pcs Paper balls
φ50-70(100*110)
Test 5times
Discharge ≧4times
⑥sponge Discharge ａｌｌ①Clean-up performance
②Discharge performance
250pcs of φ20pp
Balls.5times
Discharge ≧90%
φ50Ball
Discharge
Large Flush
12sheets
Test 5times
Discharge all
-
Vietnum
TCVN6073,5043
6
5.Requirements for discharge & clean-up performance in
each country (extract)
Japanese discharge standard is slightly lower than the other countries Clean-up
standard is nearly equivalent in each countries

4. 4
７
Ｔｒａｎｓｐｏｒｔａｔｉｏｎ ＴｅｓｔＣｏｕｎｔｒｙ Enactment Division
fixed before
2003,revised
in2013
Compulsion
Compulsion
Option
Cｈｉｎａ
ＵＳＡ
Indonesia
Jａｐａｎ
adoption of ASME in 2015
Φ100mm drain line
Φ100mm drain line
With PP ball
With toilet paper
6.Requirements for transportation performance in
each country (extract)
fixed in 2005
,no revision
since then
fixed in 1980,to
test with sponge
media
revised in 2001, to
test with rolled TP
revised in 2011, to
test with piled TP
2 kinds of test methods, one depends on ASME(PP ball) & another toilet
paper(TP). Japanese incline level is severer than the other.
Vortex-like rotation flow can effectively clean up bowl surface
Rim-less profile to get effective rotation flow
８
7-1.Reference : Coexistence of easy clean-up of bowl surface
and flushing performance
Japanese companies realize high performance water closets both with
discharge & transport performance
Conventional
Many water flows from
many small holes in rim

5. 5
排出性能
Floor Drain Trap Type
Optimization of main parts can realize it !
Wall Drain Trap Type
bowl profile bowl profile
drain socket trap profile
7-2.Reference : Coexistence both of Discharge &
Transport performance
Optimization depends on every company’s know-how
９
排出性能
One example of optimization : quick & strong siphonage for effective discharge
0
100
200
0 5 7
時間 [sec]
TIME（ｔ）→
Current 6L type
Conventional 10L type
Conventional 8L type
Short period
strong
7-3.Reference : Coexistence both of Discharge &
Transport performance
Strong & quick discharge can realize maximum transport performance
In case of siphon type
Water closet
１０
Waterquantityrate
ℓ/sec
(∝strengthofsiphonage)

6. 6
排出性能
Measurement device
Weight sensor
discharge rate & displacement are measured
with Weight sensor
7-4.Reference :Method for discharge property
Test method
according to SHASE rule
１１
Pressure
reducer
Pressure
gauge
Flowmeter
Supply
line
Water closet
Base frame
To memory device
vessel
Weight sensor
number of corner
=２
■Media in stead of waste
piled toilet paper designated by JIS
P 4501 to 4pcs.
■ Spec. of piping （BL BLT WC 2010）
size 75A
connector 90°bigger bend elbow
Incline 1/100
Total length 18m
■Companies
・ASAHI EITO
・Janis
・ＴＯＴＯ
・Panasonic
・ＬＩＸＩＬ
８‐１. Transport performance test method according to BL standard
test according to
BL standard
１２

7. 7
６L洗浄動画
<acceptance or rejection>
Mean transportation distance of 5times ≧10m
( removing maximum & minimum values)
Water closet with a tank
（approx.5L）
Water closet with a tank
（approx.6L）
８‐２. Transportation test according to BL std.
１３
Test results of water –saving TypeⅡ
(removing maximum & minimum values ) unit:m
Nominal
quantity
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
6L
5L
United
data
BL std.≧10m
11.1～18.0
Ave.16.0
12.2～18.0
Ave.15.3
Totalline
length
（
１
８
ｍ
）
11.1～18.0
Ave.15.7
Transportation distance of TypeⅡ is 11.1m～18m. Average is 15.7m
８‐３. Transportation test according to BL std.(Results)
TypeⅡ has enough ability to pass the BL std.
１４

8. 8
＜Plumbing＞
5m length straight line
10m length plumbing with 2 corners
9-1.Refference :Series Water closets(outline)
On the assumption of commercial buildings
１５
５L type ６L type
メディア（代用汚物）
BL Piled single toilet papers
0.9m×4pcs. (total 3.6m)
BL std.
D Piled single toilet papers
1m×6pcs. (total 6m)
Load of
1.6times of BL
D‘ Piled double toilet papers
1m×6pcs. (total 12m)
Load of
3.2times of BL
Washdown type
qd： 1.31L/S
Qmax： 1.49L/S
Washdown type
qd：1.3L/S
Qmax：1.4L/S
＜Test sample & Media ＞
9-2.Refference : Media
１６

9. 9
Independent
Transportation
of every WC
６．試験概要（技術部会編集）
Simultaneous
transportation
Basic
performance
5m line ■influence of line incline
■influence of connector profile（backflow）
■Necessity of air vent paipe
Transportation distance with every media
10m line
Simultaneous discharge in combination
NO.1～NO.5 WC with every media
10m line
Line clean-up flush of NO.1WC after
1,3,12hr of Latest discharge to take big
media away
Tested with various kinds of conditions
(line type ,media , simultaneous discharge・・)
Line clean-up
flush
Mentioned later for further details
9-3.Refference : Test contents
１７
5m line
10m line
5m line
45°Y-shape T-shape
Back-flow ratio ≒ 20% Back-flow ratio ≒ 50%
Adoption of easy-fｌow profile connector can be very effective for transportation
Flow direction
WC①
WC④
4.8L
＋
Y
６L
＋
T
WC①
WC④
① ④
Approximately equivalent performance
Influence of connector profile
(back-flow phenomena)
９‐４. Reference : Test Results
１８
Flow direction