Discussion on scope of rainwater harvesting to meet SDGs �in South Asia

Drinking Water Supply status globally

and in South and East Asia (JMP 2021)

Han Heijnen

President IRHA

han.heijnen@irha-h2o.org

Zomba,Malawi

Water is central to achieving SDGs

Rainwater Harvesting

UNEP. (2009). ‘Rainwater Harvesting: a lifeline for human well-being’ suggests:

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• Consider rainfall as an important manageable resource in water policy and strategy
• RWH ‘no silver bullet’, but complementary
• RWH is a local intervention: stakeholder consultation and public participation are key !
• Create equity, include the (land-)poor
• Establish enabling policies and cost-sharing, and provide technical know-how

Rain Water Harvesting

Essential part of Integrated Water Resources Management (IWRM)

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• As a decentralized source for domestic use

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• For aquifer recharge/soil and moisture conservation
• For watershed/springshed restoration and improvement
• For raising ecosystem quality and productivity
• In synergy with agriculture enhancing food security
• Slowing run-off & mitigating flooding, less disasters
• To improve urban drainage management

Watershed restoration and improvement

Maharashtra, India

Photo IRHA

Tigray, Ethiopia

Photo Woldearagay/3R

Reaching out to the last unserved

The remaining SDG challenge !

How to provide the last 7% with water?

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Communication and water education:

Engaging and informing society to conserve and save water

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Advanced planning & technology to reduce future water stress:

• Domestic/homestead RWH systems
• Facilitate storing of water: ponds, lakes,

managed aquifer recharge

• Integrated water resource management

and watershed/ecosystem protection

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Good use of rain will make the difference !

The world can not afford to waste it !

Source: 2017 and 2022 JMP report

6-8% of service can

be RWH based (IRHA)

Incl. 1.3% RWH (2017)

Incl. 2.4%

RWH

(2017)

World

Least

Developed

Countries

Surface water

Unimproved

Limited

Basic

Safely Managed

Why Rainwater Collection and Storage ?

• (Semi-) Arid Areas, Higher Elevation
• Retention and conservation for survival:

household & agriculture

• Bad Taste :
• Salinity: coastal belts, small islands
• High iron content of groundwater
• Better Service : Urban & Rural
• Storage gives water security at home,

bridges (seasonal) water shortage

• Substitution : Arsenic, Fluoride, CKDu
• Saving money and ecosystems

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In the last 2 decades: managing rain in the city, retention,

slowing down discharge, Reduce, Recharge, Reuse (RRR)

Target

6.1:

Drinking-water

By 2030, achieve universal and equitable access to safe and

affordable drinking water for all

6.1.1: Population using safely managed drinking-water services

Definition: Population using

which is:

an

improved

drinking

water source

•

•

•

located on premises,

available when needed, and

free of faecal and priority chemical contamination

·. '·,

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Accessibility

Availability

Quality

?

from Rain Water

Affordability

13

Globally 7 out of 10 people used safely managed drinking water services in 2015

washdata.org/monitoring/drinking-water

When all fulfilled

MDG

BASIC

SERVICE

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FREE FROM CONTAMINATION

AVAILABLE

WHEN NEEDED

ACCESSIBLE

ON

PREMISES

SDG

SAFELY

MANAGED

SERVICE

World

Water

Supply

Status

2015

(JMP17)

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Scope for RWH ?

3 out of 10 people are still waiting for safely managed drinking water services in 2015; and 1 in 10 has no or a poor service !

Source: WHO-UNICEF JMP July 2017

World

Water

Supply

Status

2015 in %

(JMP17)

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World

• The easy projects are already completed

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• Rainwater harvesting may well be part of the service

Solution: Sometimes it is the only solution

• And often it is complementary, enhancing

water security and livelihood options

To achieve 6.1, the world needs rainwater harvesting !

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JMP water supply coverage data (2020)

India: 0.1% RWH

Nepal: 0.3% RWH

Rural: 0.2 % RWH

Service gap 11%

Rural: 1.4 % RWH

Gap 9%

Sri Lanka: 4.8%

Rural: 5.7 % RWH

(2012), Gap 9%

Pakistan:

0.1% RWH

Rural: 0.2 % RWH

Gap 11%

Plenty of scope to increase use of RWH for domestic use in rural areas

in hill areas, even though it rains only 4 months of the year.

Except Sri Lanka that has bimodal rainfall and can also increase RWH

further in hill areas, in the dry zone and to combat CKDu (chronic kidney

disease of unknown origin, which appears to be avoided when drinking rainwater)

Bangladesh 0.5%

Rural: 0.6 % RWH

Gap 2%

Malawi (JMP 2022)

Malawi (JMP 2022)

Urban

Reaching out to the last unserved

The remaining SDG challenge !

How to provide the last 7% with water?

​

Communication and water education:

Engaging and informing society to conserve and save water

​

Advanced planning & technology to reduce future water stress:

• Domestic/homestead RWH systems
• Facilitate storing of water: ponds, lakes,

managed aquifer recharge

• Integrated water resource management

and watershed/ecosystem protection

​

Good use of rain will make the difference !

The world can not afford to waste it !

Source: 2017 and 2022 JMP report

6-8% of service can

be RWH based (IRHA)

Incl. 1.3% RWH (2017)

Incl. 2.4%

RWH

(2017)

World

Least

Developed

Countries

Surface water

Unimproved

Limited

Basic

Safely Managed

Water quality

• Generally good if system is well designed and constructed with first flush, inlet filter, etc.

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Forthcoming

Sanitary inspection based

A rainwater collection system

Maintenance and prevention

• Trimming/cutting branches from trees near roof
• Cleaning out the gutters.
• Avoid standing water
• Manage the first flush !
• Check/replace filter media.
• Check for cracks, leaky tap, mosquito screen, cover, etc.
• Clean out the tank, every 2-3 years, but do check inside of the tank regularly.

Components

• Roof and gutters/leaf guard
• First flush
• Simple filter or muslin cloth
• Tank materials
• Underground tanks
• Tank inlet, outflow,
• Overflow
• Mosquito proof/covered

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Critical: Quality of Design, Construction and Plumbing