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Rain Water as a Safe Drinking Water

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Tanuja Ariyananda,

Chief Executive Officer

Lanka Rain Water Harvesting Forum

Rain Center

41/12, New Parliament Road

Pelawatta, Battaramulla

www.lanakrainwater.org

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COLLECTING RAINWATER WHEN AND WHERE IT FALLS FOR USE DURING DRYMONTHS

  • Storage
  • Recharging

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RAINWATER HARVESTING

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Rural Tanks

Segmented Tank

Partial Underground

Brick Dome

Ferrocement

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Other RWH tanks

Overhead Tank

PE (Plastic) Tank

Barrel tank

Clay Tank

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Distribution of Rain water Harvesting Systems in Sri Lanka

  • ADRA - Adventist Development & Relief Agency Sri Lanka
  • Asia Onlus -
  • BLIA - Buddha's Light International Association
  • Care International
  • CWSSP - Community Water Supply & Sanitation Project
  • Ekamuthu Cultivators
  • GTZ - GTZ
  • HKL Menike
  • IOM -
  • Practical Action
  • KOPBMO - Kala Oya River Basin Management Office
  •  LRWHF- Lanka Rain Water Harvesting Forum
  •  NCC - National Christian Council
  •  NGO Water Supply and Sanitation Decade Service
  • NWS&DB - National Water Supply & Drainage Board
  • ORDE - Organization for Resource Development and Environment
  • OXFAM
  • PALM Foundation
  • Plan Sri Lanka
  • PRDA - People’s Rural Development Association
  • Sarvodaya –
  •  SDA - Southern Development Authority
  •  USIP - Urban settlement Improvement Project
  •  WV - World Vision
  • WaSSIP

Approx. 49,000

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  • National Rain Water Policy and Strategies, June 2005
  • ……aimed at encouraging communities to control water near its source by harvesting rain water
  • Kandy Declaration, by SAARC Ministers, September 2007
  • ……Signed by 5 minister of SAARC to promote RWH in their prospective countries
  • Amendment to Urban Development Authority Drainage Act No.36, of 2007 published by gazette September 2007
  • 15th SAARC Declaration, August 2008

…. at the looming global water crisis, recognized that South Asia must be at the forefront of bringing a new focus to the conservation of water resources. …….they directed initiation of processes of building and encouraging of research, combining conservation practices such as rain water harvesting, water conservation……

Legislation: Amendment of UDA by laws to incorporate RWH April 2009

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Policy and Legislation

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Rainwater Quality�How Rainwater can get contaminated

  • Atmosphere
  • Roof
  • Tank
  • Extracting

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Microbiological

contamination

Chemical

contamination

Carried by vector

Blown dust

Rooftop

Direct Entry

into tank

Residence in the tank

Carried by water entering the tank

Washed out

of air

Tank outlet

Ingestion

tank environment

First flush

Filters

Overflow diversion

Inlet arrangements

Screens

Screens

Outlet arrangements

Post-tank processing

Roof environment

Environmental reduction

Barriers

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Microbiological contamination

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Microbiological contamination

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Roof Contamination Prevention

“Leaf Beater”

Gutter Ball

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Debris Filter

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Different fist flush used

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  • flush out the first 2.5 mm of rainfall

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Defense for Contamination

1

2

3

4

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LOCATION

pH

Conductivity

μ C/cm

Turbidity

NTU

Hardness

CaCO3 mg/l

F.Coliform/ 100ml

MATARA

8.2 (6-9.8)

60 (10-160)

<5

0-20

28 (0-2000)

BANDARAWELLA

7.8 (7.1-11.5)

70 (30-170)

<5

0-20

11 (0-400)

WELIMADA

8.4 (10.7-7)

100 (60-160)

<5

0-20

75 (1-600)

SIYABALADUWA

10.7 (6.5-11.5)

220 (110-770)

<5

0-20

0 (0-10)

PUTTLAM

9.3-9.8

10-360

<5

20

5

VAUNIYA

9.6 (8.9-10.6)

9.6 (57-348)

-

-

22 ( 0- 120)

MEE OYA (Sulochana E.I.L etal 2022)

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6.84 (4/9-8.7)

39.56 (28.5- 588)

0.89

(0-2)

-

8.33 (0-99)

WHO Rec. Standard

6.5-8.5

500

<5

250

0

SL Standard

7- 8.5

750

<5

500

0

Water Quality Survey Results

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Measured Quality

UNDP Survey 2018

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UNDP Survey 2018

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UNDP Survey 2018

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Rainwater quality

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Improvement of Quality in a Rainwater system

  • Good O&M and awareness raising
  • First flush and inlet filter
  • Lid/Cover to prevent algae formation and insect breeding
  • Prevent metal contamination from roof
  • Simple treatment of drinking water ( boiling)

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Functioning of Rainwater Harvesting Systems

National Survey 2011

UNDP Survey 2018

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Reasons for the Use of Rainwater

  1. No alternative water sources
  2. Drying up of alternative water sources during dry periods
  3. Convenient to use at homestead
  4. Prefer to use rainwater
  5. No one available in the household to carry water from outside
  6. No cost involved
  7. Low quality of water in the alternative water sources
  8. Other reasons

National Survey 2011

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UNDP Survey 2018

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Challengers for Promoting RWH for Drinking

  • Dengue/ mosquitoes larvae breeding
  • PFAS in rainwater?
  • Metal Contamination from roof/atmosphere
  • No water quality check of RWHS

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Rain water Harvesting : Solution

  • To achieve SDG for Water Supply & Sanitation
  • Climate Adaptation for drought and floods
  • Reduce health problems due to drinking contaminated water
    • flourosis and kidney problems
  • Urban areas reduce expenditure on water and energy and to control floods

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