Foreword

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This document was prepared by Technical Committee ISO/TC 282, Water reuse, Subcommittee SC 2, Water reuse in urban areas.

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Introduction

As population increases and urbanization, industrialization, and climate change are intensifying water scarcity, water reuse presents an effective solution to the pressing issue of severe water shortages. In many regions, reclaimed water has emerged as an important alternative water resource for sustainable socio-economic development. Landscaping use is one of the major applications of water reuse in many regions, because it not only alleviates water shortages, but it can also maintain ecological flow and improve the local aquatic environment and ecosystem.

The landscaping use of reclaimed water includes urban stream flow augmentation (e.g. rivers and lakes), aesthetic impoundments and wetlands replenishment. The benefits include ensuring ecological flow to help protect urban rivers and lakes from drought, recovering natural assets, expanding the size of aquatic habitat, and improving urban aquatic spaces and scenery.

Despite the advantages of landscaping with reclaimed water, challenges can arise if the design, construction, and management of reuse projects are inappropriate. Compared with traditional water sources, reclaimed water can have variations in composition depending on the season, and to some extent it can contain pharmaceutical and personal care products which can pose potential risks to human health and the aquatic environment. Therefore, the risk associated with reclaimed water should be controlled in terms of water quality and quantity. Guidelines for water quality and quantity should be developed to ensure the safe, stable, and efficient use of reclaimed water.

This guideline is developed for the landscaping use of reclaimed water. It provides professional guidance to ensure the safe, stable, and efficient application of reclaimed water for landscaping, addressing water quantity, quality recommendations, supplemental treatments, and management practices. Utilizing reclaimed water for non-potable use, such as landscaping, is a win-win situation.

1 Scope

This document provides a guideline for good design and practice for urban reclaimed water that recharges into landscape water, including urban stream flow (e.g. rivers and lakes), aesthetic impoundments and wetlands replenishment, to ensure the proper support of the aquatic ecosystem. This document covers urban stream flow and leisure with possible incidental body contact. It does not cover urban irrigation, such as the irrigation of elements of the natural environment, urban public areas, or residential areas. It does not cover the cultivation of aquatic plants or animals for food purposes, including their sale.

This document provides recommendations for reclaimed water for landscaping uses, including those for planning, design, management, and maintenance.

2 Normative references

3 Terms and definitions

4 Abbreviated terms

5 General recommendations

5.1 General

5.2 Safety

5.3 Ecological rationale

5.4 Greenhouse gas (GHG) emissions

5.5 Aesthetic considerations

6 Hydraulic design considerations

6.1 General

6.2 Assessment of reclaimed water quantity

6.3 Hydraulic retention time (HRT)

6.4 Flow patterns

6.5 Input point of reclaimed water

7 Water quality considerations

7.1 General

7.2 Routine water quality parameters

7.3 Specific water quality parameters

8 Supplemental treatment

8.1 General

8.2 Decolourisation

8.3 Disinfection

8.4 Odour removal

8.5 Turbidity removal

8.6 Nutrients removal

8.7 Other supplemental treatments

8.8 Practice considerations for treatment selection and operation

9 Management

9.1 General

9.2 Management of water quality and quantity

9.3 Notice

10 Emergency response plan

Bibliography