10th
International Rainwater Catchment Systems Conference
"Rainwater International 2001"
Mannheim, Germany - September 2001
Moderator's Summaries of Discussion in Sessions
B1: Rainwater
Harvesting in an Urban Context
Terry Thomas
The Urban Stream comprised contributions from several continents and
complemented the mainly urban papers in the parallel fbr/ European conference.
In those contributions, most papers linked RWH with drainage, aquifer
replenishment or architectural 'greening' rather than with domestic water
supply. Several industrial and developing countries are suffering from
falling or polluted aquifers for which problem injecting runoff water
through wells assist (other countries have instead a problem with rising
aquifers that such injection would only exacerbate).
There was little discussion of affordability, especially in a developing
country context, and the contrast between industrialized-country system
budgets of over 3000 Euro per household and the system budget ceilings
likely to apply in tropical cities (under 150 Euro) was striking. The
urban sessions also did not directly address water quality, but it was
clear that in Europe urban roof water is unlikely to be used for drinking
whereas in developing cities it is potentially the cleanest water available
to dwellers in slums or in peri-urban areas.
Some special niches were identified as being available to immediate occupation
by RWH. These included industrial water supply in areas reaching the limits
of the surface or groundwater supply and domestic supply in those suburban
areas or rapidly-growing cities not yet served by heavily subsidized piped
water. RWH was shown to have the potential to reduce the costs of drainage
provision in new housing estates and to significantly improve the ecology
of large urban institutional sites.
In developed countries, urban RWH expansion is being driven by professionals
like architects. In the cities of less developed countries the process
is hampered by householder ignorance and their difficulty in finding competent
installers. 'Informal' (spontaneous) DRWH in such cities is thought to
be widely practiced but was not discussed. It was generally felt however
that supplies from conventional water sources are unlikely to be able
to keep up the rapidly growing populations of cities in poorer countries.
B2:
Rainwater Catchment (RWC) in Humid and Arid Regions (HARs)
Johann Gnadlinger / Tanuja Ariyananda
Most of the previous IRCS Conferences took place in HARs where RWC was
invented thousand of years ago. The poster sessions and presentations
showed experiences of RWC in the HARs also in the German conference: they
showed many successful projects and experiences worldwide.
Special discussion points and topics:
- Mostly RWC for domestic purposes
- The value and price of water is discussed worldwide: valuing rainwater
also
- Participatory / holistic approach: communities, women, the poor, nature
- Social, economic and health benefits of RWC
- Operation and maintenance of RWCS is cheaper than other systems
Controversies:
- Funding of projects by NGOs or/and by government
- Managed totally by the communities
- Governmental commitments
- Rain water collection is just not roof water collection (Subsurface
dams, courtyard collection, rainwater use for livestock, etc.)
- What type and size fits best for the people (it depends on climate,
people, economy, etc.)
Further discussion is needed as regards:
- RWC and water supply security
- RWC modeling
- Multiple sourcing of water supply (rain water harvesting as partial
source)
- Economic valuation of RWC
- Involvement other than English speaking people (French, Spanish, Portuguese,...)
B3:
Water Quality of Harvested Rainwater (for Drinking)
Jayne Heyworth
The overall theme of the water quality sessions was " towards a
health risk assessment of harvested rainwater". The series of presentations
contributed data on various aspects of Health Risk Assessment including:
Bacteriological risks, chemical risks and victor-borne diseases.
The key questions that guided the three water quality sessions were:
- What data inputs do we need for a health risk assessment of harvested
water quality?
- What do we know now?
- What are the gaps in data?
Lessons learnt:
- Guidelines on harvested rainwater quality are needed from World Health
Organization and to assist people in following a risk-assessment approach.
However these guidelines should focus on the process rather than be
misused as standards. Social and political considerations are needed
in undertaking a risk assessment approach.
- Hazard Analysis and Critical Control Points (HACCP) as used in the
food industry offers a methodology to guide us on process of risk assessment
, and the potential to avoid or reduce risks associated with harvesting
rainwater. A Sanitary survey and process monitoring is recommended in
this respect.
- No one risk assessment will be adequate as each site may be associated
with different risk. Hence the process is important rather than pass-fail
standards. Caution should be taken to ensure to assess site- specific
risks and take the appropriate mitigation measures.
- Guidelines for Domestic Rain Water Harvesting should describe good
practice in design and maintenance of the system. Bacteriological testing
is obviously useful in the context of research, but it has limited use
for monitoring.
- In one study, epidemiological research showed that children taking
rainwater have 32% less chance of having a gastro-enteric episode than
those using public piped water in South Australia. This type of research
is very useful for policy development and should be undertaken elsewhere
as well.
- Chemical quality of roof water, especially lead, cadmium, zinc and
pesticides needs to be considered but should be done to check once in
a while and only when one suspects chemical contamination due to human
settlement, industrial or agricultural activities.
- Vector borne diseases are a risk in rainwater harvesting in certain
climatic zones and needs to be carefully considered in rainwater harvesting
programs.
- For final treatment of rainwater, Solar Disinfection (SODIS) and appropriate
filters can be considered to make the water finally fit for drinking.
B4: Water Harvesting
for Agriculture, Including Environmental Aspects
Andrew Lo
There were altogether 26 papers (both oral and poster) presented in the
B4 session. The major discussion points touched upon topics such as:
- Selection of appropriate rainwater harvesting techniques in arid and
semi-arid areas
- Efficiency of plant barriers on runoff reduction
- The best catchment surface materials for rainwater harvesting
- Rainwater harvesting as supplemental irrigation in agricultural production
- Rainwater harvesting to improve crop yield and food security
- Improvement of quality of stored rainwater using natural energies
- Environmental benefits of rainwater harvesting for reducing groundwater
withdrawal
The major lessons learnt from the case studies and paper presentations
are as follows:
- With the global change affecting the rainfall pattern all over the
world, the storage component of rainwater harvesting is becoming a critical
design issue in the future.
- The precious rainwater collected needs to be used more efficiently
and effectively.
- Remote sensing, as well as field data is essential in modeling rainwater
harvesting design and planning.
- Economic and risk analyses are necessary to evaluate performance of
rainwater harvesting systems.
B5: Policy
Issues and Awareness Raising
Jessica Salas
Basic Considerations on the techniques, ideas, processes to promote rainwater
harvesting included:
- The Promotion of the multi-use of rainwater.
- In promoting rainwater for drinking, improve quality with WHO guidelines/
standards
A Two-pronged approach to rainwater promotion:
- Economic mainstreaming - As the rainwater technologies get mature
and accepted, both socially and economically, the business sector
picks up the opportunity of adding value to these technologies by
putting them out in the market. In some countries, communities are
ready for economic mainstreaming. In this case, the conference suggests:
product differentiation to reflect multi-use of rainwater and increase
customers' choice, segmentize the market to make rainwater technologies
adapt to local conditions.
- Political support - The second approach particularly needed in developing
countries is political support. This means rallying the local government,
the national government to lead rainwater utilization through policy
support and investment in public funds. Promoting rainwater in this
manner will be easier with community-based project implementation,
use of mass media, identifying local partners, and accounting for
community costs.
In implementing these two approaches, care should be taken to estimate
and monitor the impact on equity. Influential businesses could sabotage
community efforts when the two approaches collide. Local government policies,
directed by stakeholders should be able to protect the community to enjoy
their water rights.
ON LEGAL FRAMEWORKS AND THEIR IMPLICATIONS TO RAINWATER PROMOTION
Presenters and participants gave examples of the laws involving rainwater
and their implication to rainwater promotion. A summary is as follows:
- Rainwater is not even mentioned in water laws.
- There are countries where rainwater belongs to the government. Extra
permits are required for rainwater harvesting. Rainwater is not seen
as a water supply option. It is not seen as an individual human right.
- In some countries, there is a growing trend of decentralization.
Right to access water is decentralized to the community although ownership
belongs to the state.
- The enabling policy environment shows genuine interest in conservation
and reuse of water.
- Water law gives tax exemption to rainwater harvesting equipment,
supplies or activities. No property tax is imposed on these equipment.
- Water laws offer incentives in form of rebates if a taxpayer
puts up his/her own rainwater tank
- Other governments provide rainwater incentive by facilitating
financing of the rainwater tank or rainwater system.
- In Australia, rainwater is required in all public housing projects.
In a different perspective, an issue was raised that the government has
a policy not to harvest rain in a particular place because another community
is deprived. This leads to the perspective of upstream-downstream conflict
that could only be resolved when the perspective of the basin or the watershed,
or the natural rainwater catchment system is seen. This could lead to
a policy advocacy for a catchment basin management or the natural catchment,
even in dealing with rainwater harvesting. It is recommended that his
concern be taken up in future conferences of IRCSA.
The
Final Discussion
Topics, Contributions, Proceedings
Success stories are needed to be collected
- "More emphasis on socio-political background in DCs"
- "More emphasis on regional (appropriate) technical aspects"
- "For a rwh-push in Africa there's a need for more emphasis on
community management, management of water resources, technical aspects"
- "training of trainers is important and has to be addressed"
the Question of Standards
- "adopt German experiences as standards.. ?"
- "..or international ones ?"
- "we cannot have just one common standard for all, people need
a choice, there are gaps between the countries"
More powerful and practical recommendations/an agenda / one vision and
a common ground till Kyoto 2003 - what are we going to present there ?
- "success stories need to be systemized"
- "an international organisation should publish a commitment"
- "we need links with international organisations like Int Ass
for Water Quality, Int. Ass for storm drainage"
- "the voice of IRCSA is needed ("you are only heard, when
you are in the political centre")
- "need for clear and common definitions, there still is confusion
about the word rwh"
- "we need to come from rw-harvesting to rw-management"
Which form of further communication for rwh ?
- "using the internet as medium for communication"
- "activities of the members need to be written down"
- "cse is starting a e-newsletter on rwh"
- "what about a rwh-journal ?"
- "and a rwh cd-rom ?"
- "all previous rainwater conferences need to be on the net"
- "establishment of a Forum for RW Technology Transfer ?"
for further discussion/ up-dates of on-going activities you should join
|