TECHNOLOGY

Building an Ultra
Water Saving Society
Launched in 2007, the Water Security Council of Japan, or Team Water Japan, has been discussing a newwater system for a global population of 10 billion. The Building Research Institute has taken on important
related work including the development of an ultra water saving sanitary system.

F

resh water accounts for merely 2.5% of the water on Earth.
The proportion of usable
Seawater accounts for 97.5%of the water on Earth.
water in rivers and lakes is as
small as 0.01% (Figure 1).
At present, safe drinking water is
Fresh water accounts for 2.5%.
not always available to 16% of people in
Most of it exists in the form ofdeveloping countries, or to 13% of theArctic and Antarctic ice.
worldwide population. Forty-seven percent of those living in developing counWater in rivers and lakes
accounts for 0.01%.
tries or 38% of people around the worldlack reliable access to toilets and othersanitary facilities. The contamination ofwater sources with human waste exacerOnly 0.01% of the water on the entire planet is available
bates the shortage of drinking waterfor our domestic use.
(Figure 2).
In urban districts of developFig. 2: Risk of Water Resources Shortageing countries, demographic growth
Future Outlook of Worldwide
Water Shortage Risk Levels
and concentration
Water Demand
are intensifying. In
About 1.4 fold in total –these areas, it is aabout 1.8 fold
top priority issue
for domestic use
to secure drinking
OceaniaSouth America
water, to savewater by controlOceania
South America
ling water demand,and to achieve
Asia
Asia
sanitation bymeans of wastewaAfrica
AfricaNoneter treatment toNorth America North America
Low
Notes
prevent the polluEurope
MediumEurope
1. Source: Stockholm Environment Institute:High
Comprehensive Assessment of the Fresh-watertion of drinking
Resources of the World, 1997
1995
2025
No Data Available
water sources and2. This map portrays the water shortage risk
level of each country estimated from the current
infectious diseases.
water consumption in comparison with water
resources available, water supply reliability andSource: Ministry of Land, Infrastructure,compound indicators based on relations withHowever, it
state revenues.
Transport and Tourism: Water Resources
isbecoming
difin Japan (2009)
ficult to maintainthe sanitary level
Many countries will face water shortage as a result ofand to preserve
rapid population growth and social development
drinking water inthat will lead to an increase in use of safe drinking
a way that keeps
water and of toilets.
pace with popuFig. 1: Water Resources on the Earth38

Fig. 3: Water Resources in the World and in Japan

population increase has
been slowing after a
Precipitation (mm per year)
number of measures
Japan is located at the east end of Monsoon Asia, oneof the rainiest regions in the world. The country’s
were adopted.
average annual precipitation is about double theWorld
Even so, many reCanada
worldwide average of the continental area. However,
New Zealand
Japan’s total annual precipitation per capita, calculated
searchers
forecast thatAustralia
by multiplying the average annual precipitation by thethe worldwide populaSweden
national land area and dividing the resulting value by
Indonesia
the total population, is around one third the global
tion will reach around
USAaverage. The internal renewable water resources per
10 billion at the end of
Romania
capita are less than half the world average.
Austriathe twenty-first centuAustria
China and the rest of Asia face
Switzerland
ry. It is essential toThailandtake this scale of popuserious
water
shortage.
InJapan,The Philippines
Francelation into considerScarce in terms of precipitation
the precipitation and the water
Japanand water resources per capita
ation when studying
Spain
resources per capita are limited.
UKwater-related systems.
ChinaJapan has an averIndia
Average total annual
precipitation per capita
Egyptage
yearlyprecipitation
Water
resourcespercapita
Saudi Arabiaof1,700
millimeters.
1. Source: Created on the basis of Ministry of Land, Infrastructure,
Transport and Tourism: Water Resources in Japan (2009)
Notes:
That is about double
1. Source: Created by the Water Resources Department of the Ministry of Land, Infrastructure, Transport and Tourism on the basis of theAQUASTAT from the Food and Agriculture Organization (FAO).
the worldwide average.
2. Source: Statistics Bureau of the Ministry of Internal Affairs and Communications: Population Census (2005) for Japan’s population andHowever, the precipiWater Resources Department of the Ministry of Land, Infrastructure,
Transport and Tourism for the averages of the precipitation and theaaaaa
water resources in 1975-200523/
tation per capita is justabout one-third theJapan’s average annual precipitation: About double the world average
global average level.
Japan’s water resources per capita: Less than half the world average
The precipitation range
is wide, both seasonally and regionally.
l a t i o n g r o w t h a n d c o n c e n t r a t i o n nearly 6.9 billion in 2010, according to Especially in the populous Kanto region,
using the traditional approaches of the 2010 edition of the State of World the amount of water available is about aPopulation report from the United quarter of the nationwide average
different countries.
(Figure 3).
The modern water supply and sew- Nations Population Fund.
All environmental issues derive
erage system was established as a sysIn 2005, water consumption for agtem for developed countries in the nine- from population issues and problems ricultural use in Japan amounted to 54.9
teenth century in which the global with water resources are no exceptions. billion m3, for industrial use 12.6 billion
population was still less than one billion. Needless to say, population control is m3, and for domestic use 15.9 billion m3
It is premised on massive consump- ultimately essential. In recent years, the (Figure 4).
tion of waterand energy.
Fig. 4: Breakdown of Water Consumption in Japan
Given theNationwide Water Consumption
Categories of Water Consumption
limited capaci（billion m ）ty of water
Household Water
resources, thisWaterformakes it very
Domestic Use
challenging to
Water forWater for Use
Water forUrban Use
respond toin Urban Activities
Agricultural Use
worldwide
Water forpopulation
Industrial Use
growth and to
Water forIndustrial Use
Water forthe modernizaUrban Use
Water fortion of developDomestic Use
Water forAgricultural Use
ing countries.
The global
population has
Source: Created on the basis of Ministry of Land, Infrastructure, Transport and Tourism: Water Resources in Japan (2009)
been climbing
Domestic use of water is responsible for about 20% of
rapidly since
the advent of
the total water consumption. It accounts for nearly 60% of the total
the modernconsumption of utility water for urban use.
age. It reached
Total annual precipitation andwater resources per capita(m3 per person per year)

3Water for
生活用水Domestic
Use

Water for工?用水
Industrial
Use

Water for?? 用水
AgriculturalUse

Water for
都市用水
Usein Urban
Activities

Total Water
用水量合?
Consumption

39

TECHNOLOGY
Fig. 5: Japan as Global Water Consumer
Import Origins of Virtual Water
Consumed in Japan（ billion m3 ）

38.9
USA
Australia & New Zealand 8.9
4.9
Canada2.5
Brazil & Argentina
2.2
China
1.4
Denmark
1.3
Thailand & Vietnam
UAE
0.3
South Africa
0.3
Others3.3
64.0
Total1)
Reference:
Water Consumption
in Japan（参考）日本国内的用水量1)（ Hundred million m3 per year ）Water for Industrial Use
Water for
Domestic Use
0200400600800

Virtual water imports in 2000
(Unit: hundred million m3 per year)

Water for Agricultural Use(Estimated by Prof. Oki Taikan from statistical
data in the 2000 Food Balance Sheet)
1000

Source for 1): Ministry of Land, Infrastructure, Transport and Tourism:
Water Resources in Japan (2009)

Japan imports as much as 64 billion m3 of virtual water in a year.
This quantity surpasses the quantity of water consumed for
agricultural use in the country.
(Japan’s food self-sufficiency is about 40%.)
In Japan, agriculture is responsible
for a very large percentage of water
consumption, yet the country’s foodself-sufficiency is as low as about 40%.
Imports of agricultural and livestock
products effectively means that Japan
consumes the water required to produce
these products. This concept of water iscalled virtual water. *1 As a food importer, Japan consumes a huge amountof virtual water by importing food.
At the moment, Japan imports asmuch as 64 billion m3 of virtualwater per year, which surpasses theannual water consumption of 54.9
billion m 3 for domestic agriculturaluse ( Figure 5).
Improving Japan’s food self-sufficiency would require extra water
resources, but efforts to cut industrial water consumption are nearing
their limit.
On the other hand, domestic water
consumption accounts for about 20% of
total water consumption in Japan, andurban water consumption for around
60% of total utility water consumption.
They suggest that there is sufficientroom for reducing this consumption.
To prepare for water shortages caused
by abnormal climate conditions and forthe suspension of water supply after adisaster, it will be vital to reduce this40water consumption.
Because of climate change, circumstances surrounding water resources areincreasingly uncertain. To effectively
utilize water sources and build a social
foundation that is resistant to various issues arising from the water resources, itis necessary to work strategically to secure water sources and to make effective
use of water.
In Japan as well, these issues attracted public attention as a matter ofwater security and became increasingly
recognized as pressing problems. In
2007, the Water Security Council ofJapan (WSCJ), also known as Team
Water Japan for Global Water Security,
was established.
Constructing a Water System for
10 Billion People

A study of a water system designed
for the world population of 10 billion
has only just begun. Many different
investigations are underway in separate related domains. They range fromresearch to improve existing watersupply and sewerage technologies to
eco-sanitation technologies such ascompost toilets.
Initiatives for ultra and hyper
water saving in buildings have beensporadically implemented
in areas facing difficulty inwater supply and for economic reasons. They arehelpful to construction of awater system that can serve
10 billion people in manydifferent respects, including
minimization of the watersupply and sewerage infrastructure, advanced and recycling treatment of wastewater taking advantage ofthe effect of the reductionof the wastewater volume,and prevention of environmental contamination withsewage water by means ofseparated treatment.
The ultra water saving
technology in buildings isconsequently drawing attention as one of the fundamental technologies of a water
system for 10 billion people.

Ultra water saving and its benefits(i) Ultra water saving for reducing water
consumptionDomestic water consumption constitutes about 60% of water consumption for urban use. Nearly 80% of itis household water and the remaining
20% is for use in urban activities.
Household water consumption
could be lowered to around 50% of
the current level by intensively using
water saving technologies.
The water consumption of thesewage water treatment line may be
cut by 95% or more. In addition tomere water saving, the option of fullrecycling and reuse on site is becoming viable in economic terms.
(ii) Ultra water saving for reducing theburden on the existing water supply
and sewerage infrastructure
Water saving in buildings is expected
to reduce the burden on the existingwater supply and sewerage infrastructure as well as long-time social costs
for operation and maintenance.
(iii) Ultra water saving for easing theburden for infrastructure
construction
The economic burden for the con-Fig. 6: Trend in Flush Water Volume for Toilet Bowls

Liters per flush

1413 13

Flush water volume (large)

12

Flush water volume (small)

10

10

888
6

6

65

5.5
4.5

4

4.8

4201976

1996

1999

struction of new infrastructure can be
minimized by planning a minimized
water supply and sewerage infrastructure premised on buildings that incorporate water saving technologies.
(iv) Ultra water saving for reducing theimpact that pollutes the water environment
It is possible to attenuate the environmental impact by introducing advanced treatment with sewerage, septic tanks and suchlike, and to treat
nutrient salts by capitalizing on thesurplus capacity of the existing treatment facilities generated from thewater saving.
The water saving will also dramatically boost the applicability ofrecycling treatment technology,
which hitherto has not been economically viable. It also enables aseparated treatment technology involving individual treatment of thesewage water.
Given these social circumstances, the Water Security Council ofJapan (WSCJ), or Team Water
Japan, launched in 2007, has been
discussing a new water system for a
global population of 10 billion. At
the Water Week Commemorative
Symposium organized by theMinistry of Land, Infrastructure,
Transport and Tourism in July 2010,
it proposed the construction of awater saving society.
On the basis of that suggestion,
the Takumizu Team, represented by
Sankai Toshihiro of the Building
Research Institute, was registeredwith the WSCJ in February 2011 as a
new action team aiming at building awater saving society. It recently com-20062007

2009

menced its activity.
Technological Development
Relating to Ultra Water Saving inBuildings by the Building ResearchInstitute

The Building Research Institute has
been studying the construction of awater saving society in collaboration
with the industrial, governmental andacademic sectors through its activities inTeam Water Japan and in the Water
Week Commemorative Symposium.
With respect to water saving, considerable progress was made in technical development by technological development efforts in the private sector.
For further stepping up the water saving, it is indispensable to overcome
technological issues involved in watersaving, ultra water saving and hyper
water saving.
Take the western-style toilet bowl
for example. The latest model produces
a significant water saving effect as it
consumes less than half the amount ofwater consumed by the 1976 model in asingle flush (Figure 6).
However, with this water saving
toilet bowl, the wastewater drainpipe
could be blocked. That prevents it frombeing used in any non-residential applications. The wastewater piping for nonresidential applications is more complicated and longer than that for residentialuse. Paper consumption is relatively
larger in non-residential applications.
Moreover, even if it is confined toresidential use, it has a drawback in
waste conveyance performancethrough the wastewater piping. It isdifficult to reduce water consumption
beyond about five liters per flush.

Toilet bowls for aircraft, trains andsuchlike with a flush water volume ofseveral hundred milliliters or less per
flush have already found practical use.
They used a special technology that
averts the problem on waste conveyance in the wastewater drainpipe.
To improve water savings in residential and other buildings, it is essential to eliminate the bottleneck of waste
conveyance through wastewater piping,while still meeting the legal requirements on sanitary performance inbuildings. Studying not just the toilet
bowl but the entire system, including
wastewater piping, is indispensable.
The application of technologies usedon aircraft and trains to buildings mustalso be studied.
The Building Research Institutehas developed a system with a hyper
water saving toilet bowl consuming
600 milliliters or less of water per
flush. It is designed to address theproblem with existing individual septictank. Figures 7 and 8 illustrate an example of its achievements.
On the basis of the research findings, the Building Research Institutewill be continuing its research and development activities to resolve technicalissues on the system of ultra water saving sanitary equipment in buildings.
The purpose of these activities is tohelp use water resources effectively andto reduce the impact on the environmentby clearing the technical hurdles associated with a system of ultra water saving
sanitary equipment in a building. This isa first step towards creating a societythat conserves water, in anticipation of aworld population of 10 billion.
The focus of the study is a systemof hyper water saving sanitary equipment, comprising:(i) Apparatuses and devices with low
water consumption, such as an ultra
water saving toilet bowl with a flush
water volume of around five liters, ahyper water saving toilet bowl with aflush water volume of about 600 milliliters, and water circulating bathtubsand dishwashers that achieve hugewater consumption cuts;(ii) Water supply and wastewaterequipment compatible with ultra andhyper water saving devices; and(iii) On-site wastewater treatment
41

TECHNOLOGY
Fig. 7: Water Saving Wastewater Treatment System for Household Use
Compatible with Existing Tandoku Jokaso*
Hyper water saving toilet bowl

Impacts on the water environment(600 ml per flush)

Pump

Piping cleaning water

Nitrification
systemExisting
Tandoku Jokaso*
Miscellaneousdrainage system(water savingtechnology)

Biological oxygen demand (BOD):
10 g/day or lessTotal nitrogen (T-N):
10 g/day or lessTotal phosphorus (T-P):
1 g/day or lessWastewateror treatedwaterHigh concentration
wastewater
Low concentration
wastewater

Denitrification
system for highconcentration
wastewater
Simplified treatment

Soil treatment for preventing
groundwater contamination
before discharge

Discharge* Wastewater treatment system only for black water

Fig. 8: Wastewater Pipe Cleaning System Ensuring Waste Conveyance
Hyper water saving toilet bowl
(600 ml per flush)

Pump
Wastewater or treated water(piping cleaning water)

Waste conveyance
ExistingTandoku Jokaso** Wastewater treatment system only for black waterequipment with ultra and hyper watersaving performance.
With regard to onsite wastewater
treatment equipment with ultra andhyper water saving performance, consideration will be given to separate
human waste treatment facilities in regions served by sewerage systems andto wastewater treatment facilities designed for developing countries.
Technologies for planning, designing and evaluating the system ofhyper water saving sanitary equipment and those for assessing the basic
technologies that constitute the system will be established.
It is said that the twenty-first century is an era of water. Preservation andeffective use of water resources are anissue of international significance.
The world is facing a universal
challenge of surpassing the modernwater supply and sewerage systemthat was created in the United
42

Kingdom in the nineteenth century
and that now stands as a de facto
standard in today’s society.
It would be difficult for the traditional modern system of water supply
and sewerage to support a global population of 10 billion. With respect to flush
toilets, however, research is underway
on the issues of:(i) Toilet systems free from water
consumption, such as the dry toilet or
the composting toilet;(ii) Toilet systems with hyper watersaving toilet bowls for minimizing
water consumption; and(iii) Toilet systems with fully cyclicuse of water.
The Building Research Institute is
striving to create an ultra water saving
sanitary system that corresponds to thesystems mentioned in (ii) and (iii)
above. It comprises technology for ultra-low water consumption throughout
the building, including toilets, andtechnologies forthe reuse and fullrecycling of waterand for separated
wastewater treatment that can be
introduced as a result of the ultralow water consumption. Basedon a simple andplain concept ofultra water saving,a feature of thissystem is that it
can be effectively
used to upgrade
modern water supply and seweragesystems and build
distributed on-site
treatment systems.
Civilized society is vulnerable todamage caused in
the event of disaster. Should theelectric power orwater supply andsewerage systemfail, it is difficult
even to maintain aliving environment
with a minimallevel of sanitation.
In any event like this, assistance tovictims and the burden on infrastructure
may be eased considerably if the sanitary living environment needs lesswater. Water saving and ultra watersaving will work very effectively in thecase of providing toilets and other sanitary facilities with a function thatmaintains minimum functionality evenin a disaster.
It is believed that the question of securing the ability to respond to damage
from disasters and other events should
also be scrutinized at the time of studying water saving and ultra water saving
measures in buildings.
Notes: 1. Virtual water. Virtual waterrefers to the volume of water required
for the agriculture and livestock that isregarded as being traded at the time ofimporting and exporting agricultural andlivestock products.