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Household Water Treatment and Safe Storage (HWTS) in Emergency Settings

The project's aim is to develop an appropriate household water treatment product that is suitable for emergency response situations.

A boy drinking water from small water treatment tanks

The challenge

There is a significant body of evidence demonstrating that household water treatment along with improved water storage and handling significantly improves microbial water quality and has an critical impact on diarrhoea morbidity. In many emergency situations, chlorine tablets are distributed as a means to protect water at the household level. This is a practical and efficient solution but UNICEF would like to investigate the potential for additional filter-based products that may offer even more cost-effective water purification.

The response

Specifications for household water treatment systems in emergency settings

As there have been many notable advances in water treatment recently, UNICEF is asking if it is now possible to create a household level water treatment product that can be used in emergency settings. The following parameters have been identified that would allow Household water treatment systems (HWTS) to work emergency settings:

Affordable: Less than $20.00 per family
Easy to use: Intuitive, simple design
Fail-safe: End of life mechanism which prevents the product from providing water when no longer clean
Durable: Can withstand typical emergency settings
Packable: Minimal logistic footprint
Safe storage: Combines treatment and storage with safe dispensing mechanism
Life Span: 1 year for a family of 5 @2.5 l/d/p (4.5 m3/yr)
Consumables: Does not require additional provision of chemicals during duration of unit
Protection levels: Bacteria, virus, and protozoa protection

Gravity Driven Membrane (GDM) HWTS

One of the projects currently being investigated is a Gravity Driven Membrane (GDM) filter. GDM filters offer a new approach to filtration; using existing ultra-filters, they allow for the formation of a bio-film that self-cleans. This prevents the ultra filter from clogging and eliminates the need for back-flushing, which is one of the key limitations of existing ultra-filter based products. In a GDM filter, the water is filtered at a rate of 4-10 L/h/m2, due to the formation of the biofilm. Filters can be operated without maintenance for 5-8 years with most types of source water.

GDM filters have been identified as having potential to fulfill the needs listed above. The project is currently conducting a field trial at UNICEF SD to further validate the technology's suitability for UNICEF HWTS needs.