Updated Nov 25, 2018

The Clariwash Self Washing Filter

Community water supply for development and disaster response


Nigel Heeler

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Stage 4: Transition to Scale

Six ClariWash self-washing filters have been installed in western Uganda and have been operating since January 2017 supplying a community of 800 people without the need for power supply or human intervention. The design hydraulics were previously tested on a university rig and shown to work over a number of repeating cycles.

Focus Areas:

Disaster Risk Reduction, Health and Physical Development

Disaster Risk Reduction, Health and Physical DevelopmentSEE LESS



The use of relatively complex conventional drinking water treatment processes used in the developed world (for example clarification and rapid filtration) is impractical in remoter parts of the developing world due to a lack of skilled operatives, lack of maintenance parts for electro-mechanical & control systems, unreliable power supply and poor access to treatment chemicals.

Development strategies in these areas have aimed to provide improved water supplies from “safe” water sources such as groundwater accessed via. boreholes and hand pumps, capped springs, infiltration and impounded waters mainly without treatment. Whilst many gains have been made; aquifers can become polluted and shallow wells easily contaminated. In other cases, a population may continue to rely on an untreated contaminated surface water source, rather than a new borehole, simply because it tastes better, without understanding the hidden dangers. An iron laden source which is acceptable in other respects may be neglected because the water appears dirty - a treatment capability could make this acceptable. There may be merit in assessing where the existing water supplies come from before making changes.



I have attempted to address some of these issues by developing an appropriate type of water treatment for use in areas with little or no technical support and for use in disaster response. The treatment comprises a low maintenance self-washing clarifier/filtration arrangement which incorporates upstream spray aeration (when required) and downstream disinfection using a chlorine (soluble tablet feeder) together contact time. The process targets removal of micro-biological pathogens, turbidity, suspended solids, particulate iron etc. Other processes may be required to remove chemicals such as nitrates. A degree of arsenic removal may be possible using an advanced filter media together with vigorous upstream aeration.

Target Beneficiaries

For use in developing countries with low technical infrastructure and for rapid deployment in disaster response.

Mission and Vision

In support of the UN Sustainability Goal 6 Clean Water and Sanitation, the vision is to provide a low cost method of treated water provision without need for power supply or human intervention. The system is replicable and scalable. The aim is to transfer technology to local country groups for onward assembly and deployment.

Innovation Description

The Clariwash Self Washing Filter comprises a selfwashing clarifier and filter system purifying water andproviding centralised treatment to communities. Both clarifier and filter are washed by the same backwash system. It is intended forbothdevelopment and disaster responsesituations. A modular version for rapid deployment is available for local assembly or for exporting. The backwash systemhasno moving parts, operating by gravity, requiring littleto no maintenance.

Competitive Advantage

The target aims of the system are as follows:

- Community water treatment for development & disaster response

- Self-backwashing system - wash cycle cleans both clarifier and filter without intervention

- No moving parts, actuated valves, power supply or control system

- Low capital cost and low maintenance

- No chemicals other than chlorine tablets

- Assembled from locally available parts - plastic pipes, tanks, plumbing.

- Workshop assembly without a manufacturing process.

- Rapidly deployable and to remote areas with no road access

- Replicable and scalable.

Planned Goals and Milestones

Setting up local country bases where filter units can be pre-assembled as a kit of parts ready for deployment.
Provision of local prototype demonstration units.
Further testing on turbid water sources.
Contact local technical groups who wish to utilise the technology
Funding Goal10,000
New Implemented CountriesIndia, Uganda
RecruitLocal technical volunteers required - preferably water/mechanical engineers/plumbers but if not good practical skills. Other developed country volunteers who wish to help take this forward.
New FeatureAddition of tube clarifier upstream of filter to improve performance with turbid water.


Mar 2018
New Product or Service
Modular design of Clariwash filter for rapid deployment
Mar 2018
Recognition ReceivedPENDING
Date Unknown
Date Unknown
New Country Implemented In