• 
• Japanese
• 
• IETC's Focal Area
• Disaster Management
• Projects
• Publications
• News
• Waste Management
• Projects
• Publications
• News
• Water and Sanitation
• Projects
• Publications
• News
• Resources
• Publications
• About IETC
• Background and History
• Director
• Activity Reports
• Supporting Foundations
• Procurement
• Contact Us

Rainwater Harvesting And Utilisation

An Environmentally Sound Approach for Sustainable
Urban Water Management: An Introductory Guide for Decision-Makers

What Must be Considered From Quality and Health Aspects in Utilising Rainwater?

In the past, it was believed that rainwater was pure and could be consumed without pre-treatment. While this may be true in some areas that are relatively unpolluted, rainwater collected in many locations contains impurities. Particularly during the last three decades, “acid rain” has affected the quality of the collected water, to the point where it now usually requires treatment.

Rainwater quality varies for a number of reasons. While there are widely accepted standards for drinking water, the development of approved standards for water when it is used for non-potable applications would facilitate the use of rainwater sources.

In terms of physical-chemical parameters, collected roof water, rainwater and urban storm water tend to exhibit quality levels that are generally comparable to the World Health Organisation (WHO) guideline values for drinking water. However, low pH rainwater can occur as a result of sulphur dioxide, nitrous oxide and other industrial emissions, hence air quality standards must be reviewed and enforced. In addition, high lead values can sometimes be attributed to the composition of certain roofing materials – thus it is recommended that for roof water collection systems, the type of roofing material should be carefully considered.

A number of collected rainwater samples have exceeded the WHO values in terms of total coliform and faecal coliform. The ratios of faecal coliform to faecal streptococci from these samples indicated that the source of pollution was the droppings of birds, rodents, etc.

Currently, water quality control in roof water collection systems is limited to diverting first flushes and occasional cleaning of cisterns. Boiling, despite its limitations, is the easiest and surest way to achieve disinfection, although there is often a reluctance to accept this practice as taste is affected. Chlorine in the form of household bleach can be used for disinfection, however the cost of UV disinfection systems are usually prohibitive. One promising area of research is the use of photo-oxidation based on available sunlight to remove both the coliforms and streptococci.

Table of Contents

• Major Projects
• 
• DEBRI Project
• 
• Iraqi Marshlands Project
• 
• IETC's Tools
• 
• ESTIS facilitates creation and management of websites on the Internet, sharing and searching of information across multiple ESTIS websites, publishing of information by non-web designers and decentralized management of content.
• 
• WiseWater is a spreadsheet application for projecting reductions in Water Consumption Patterns after application of Environmentally Sound Technologies. It is included as part of the publication "Every Drop Counts: Environmentally Sound Technologies for Urban and Domestic Water Use Efficiency".
• 
• PAMOLARE is an environmental modelling tool to forecast the changes in water quality leading to the eutrophication of Lakes and Reservoirs.
  The versatility of PAMOLARE allows for its use in decision making process as well as for training purposes.
•