W4 1

WASH Cluster – Water in Emergencies

W

Water in Emergencies

Session 4

Water Sources, Treatment & Implications

W4 2

WASH Cluster – Water in Emergencies

W

Water Supply

Stages Water abstraction

Raw water storage

Pre-treatment

(such as roughing filtration)

Coagulation / Flocculation / Sedimentation or Slow sand filtration

Chlorination Storage Distribution

Water supply in emergency contexts may involve some or all of the above stages

Adapted form: Davies & Lambert (2002) Engineering in

Emergencies, REDR / ITDG

W4 3

WASH Cluster – Water in Emergencies

W

Criteria for selection

Water source, treatment &

supply

Ease / ability to obtain an acceptable

quality?

Impacts of development?

• Existing users• Aquifers

• Environment

Time of set up vs urgency?

• Technical• Resource / logistical

Costs?

• Capital• O&M

Ease of O&M?

• Requirements• Resource / logistical

•Availability of trained staff

Management, legal, security, socio-

political & cultural constraints?

• Management• Land ownership

• Security• Cultural & socio-political

issues

Acceptable yield?

• Demand vs yield• Seasonal yield

• Future yield

Adapted form: House & Reed (1997) Emergency Water Sources, WEDC

W4 4

WASH Cluster – Water in Emergencies

W

Shallow & Medium Depth Groundwater

Shallow well, Lao PDR

S House / ACF

Handpump on shallow borehole, Liberia

S House / ACF

W4 5

WASH Cluster – Water in Emergencies

W Springs Piped Supplies

Piped supply from motorised borehole, IDP camp, northern Uganda

S House / MSF-OCBA

Spring being protected, Zaire S House / WEDC

W4 6

WASH Cluster – Water in Emergencies

W

Deep Groundwater Surface Water

Submersible pump S House / WaterAid

Surface water sources supplying refugee camps, Zaire

S House / MSF-OCBA

W4 7

WASH Cluster – Water in Emergencies

W

Rainwater Roof collected Ground collected

Health facility in an IDP camp, northern Uganda

S House / MSF-OCBA

Birkad underground rainwater collection tank, northern Kenya

S House / AAH-US

W4 8

WASH Cluster – Water in Emergencies

W

Implications of selection of Water Source and Supply

W4 9

WASH Cluster – Water in Emergencies

W

Scenarios

1. Spring located above an IDP camp, used by the local community, sited on a private landowners land

2. Shallow wells developed in a wooded area outside an IDP camp for people displaced by a conflict

3. Water is being tankered from one part of a city which is under control of one armed group and has to pass through the area of another armed group before reaching its point of supply to a group of displaced people

4. Water is being piped from a seasonal stream being fed from a spring in a mountainous area following a major earthquake, aftershocks are still being felt

5. 100,000 displaced persons due to conflict arrive in a semi-arid area and new boreholes are drilled to supply the camps

W4 10

WASH Cluster – Water in Emergencies

W

Implications of Selection of Source & Supply

Exercise - Consider the particular scenario provided to you and consider the following:

1.What are the risks / potential negative implications apparent in the scenario and to what or whom?

2.How could you reduce the risk?

W4 11

WASH Cluster – Water in Emergencies

W

Water Treatment

• Most common water treatment = chlorination

• Chlorination works most effectively with low turbidity of 1 NTU (or max 20 NTU)

• Guidelines for chlorination given for pH<8, turbidity <5 NTU, temperature approx 20oC, 30 min retention time

• If pH higher, temp lower or turbidity higher then adjust processes

W4 12

WASH Cluster – Water in Emergencies

W

Pre-Treatment

Pre-treatment:

– Roughing filtration

– Coagulation, flocculation & sedimentation

– Rapid sand filtration

Other treatment:

– Slow sand filters - but also need pre-treatment to reduce turbidity

– Water treatment kits - various methods

W4 13

WASH Cluster – Water in Emergencies

W

Bulk Water Treatment Coagulation

& flocculation

Safety needed with chemicals…

Zaire (DRC)

S House / WEDC

Ethiopia

S House / WEDC

Pakistan

S House / OXFAM-GB

Field ‘Jar test’

W4 14

WASH Cluster – Water in Emergencies

W

Chlorination

Practical handout on chlorination provided

W4 15

WASH Cluster – Water in Emergencies

W

Household water treatment• Candle filters

• Ceramic pot filters

• Biosand household filters

• Chlorination

• Boiling

• Sodis – using UV light & plastic bottles

• Local natural coagulants Cambodia

H Jones / WEDC

Moringa Oliefera

Waterlines

W4 16

WASH Cluster – Water in Emergencies

W

Candle filter unitsOXFAM-GB

W4 17

WASH Cluster – Water in Emergencies

W

Bulk vs Household Treatment

+ -

Bulk water treatment

• Can supply to large numbers of people

• Can supply quickly

• Can control water quality

• Can monitor changing water needs

• Not useful for dispersed populations

• High O&M inputs

• Water can be contaminated post-supply

Household water treatment

• More control for householders

• More sustainable (if appropriate to situation)

• Less risk of contamination post treatment

• Good for disperse populations

• Training needed for effective use

• More difficult to supply large numbers of people

• Limited control on effective use