solution finder

solution finder


Author/Compiled by
Gabrial Erismann (Antenna Foundation)
Raphael Graser (Antenna Foundation)
Executive Summary

Chlorination, which means adding active chlorine (sodium hypochlorite) to water, is the most common method used for disinfecting of drinking water. Active chlorine destroys or inactivates most pathogenic microorganisms, including parasites, bacteria and viruses with a very high reliability. The WHO estimates that chlorination is the most secure, effective and economic option. Yet, generally speaking, chlorine is not produced in low-income countries, but imported in the form of tablets or bleach, at relatively high cost. WATA® is technology and approach developed by Antenna Foundation which integrates health education with the local production of chlorine by electrolysis (through the WATA® device) in a sustainable supply chain, making safe water treatment a profitable activity.

Local production (avoids most storage and transportation problems and environment impacts)
Generation of income for local communities (e.g. water kiosk)
Solar versions available for autonomous use
Quality control is possible at every stage of production and use
Low cost
Especially suitable for humanitarian response or war-thorn areas, where for example chlorine gas is banned.
Easy to use
Disinfectant can be used for a large range of applications (e.g. disinfecting laboratory equipment, wounds, cleaning latrines, disinfecting kitchen utensils and surfaces, washing rough fruits and vegetables etc.)
Electricity required (but can be run with solar energy)
Education and training for operators are essentials, especially when using Maxi-WATA®
Chlorination can cause the generation of a very low concentration of toxic disinfection by-products (DBPs) in the case of disinfecting water with a high organic matter content
Dosage might be more difficult than with tablets
Only clear water can be used to produce WATA® solution and the solution only effective to treat clean water
The device should only be used by a responsible person familiar with the user manual for the relevant WATA® device.
Reaction time of 30 min required before consumption after treatment
Chlorine taste and smell
In Out


Drinking Water

To prevent waterborne diseases it is fundamental to deliver safe water at the point of use. The 2017 published Joint Monitoring Programme (JMP) report from WHO and UNICEF shows that recontamination occurs very often between the point of collection and the point of use and thus leads to an increase in waterborne diseases. It is thus fundamental to find a solution to enable populations to address their drinking water problem in a self-sufficient and perennial way. To respond to the need of BoP communities to have access to simple and affordable water treatment methods at the household level, Antenna Foundation has developed a range of WATA devices (Mini-WATA®, WATA-Standard®, WATA-Plus®, Midi-WATA® and Maxi-WATA®), and control reagents (the WataBlue® & WataTest®). Until today WATA® kits have been used in over 100 countries.

WATA® Device

The Range of WATA® Devices

The Range of WATA® Devices

The WATA® is a handy, robust device designed specifically for the production of active chlorine through the electrolysis of salted water under conditions in developing countries. The resulting solution can be used for drinking water disinfection (1 Liter of chlorine per 4.000 Liters of contaminated water) since the strong oxidising power of the chlorine will destroy most of the pathogenic germs and the water will be drinkable after 30 minutes.

 Dosage for Chlorinating Drinking Water

Dosage for Chlorinating Drinking Water 

This sodium hypochlorite solution can also be used as a disinfectant for home use. The WATA® system is extremely adaptable to meeting the disinfectant needs of larger institutions such as health facilities also. Additionally, the sodium hypochlorite solution is similar to Dakin’s solution, a neutral disinfectant, and can be used directly for cleaning wounds.

Use fo WATA®

Preparation of Disinfectant Solution

Preparation of Disinfectant Solution

Preparation of Disinfectant Solution

The device requires only water, salt and electricity to function. It is important to note that clear water is a requirement for both the production process and as an input for the disinfection process. For the production process, highly turbid water will interfere with the electrolysis process and the resulting solution may not be at 6g of active chlorine per liter. If the turbidity (a measure of the suspended solids in the water) of the water to be disinfected exceeds 5 units of turbidity (NTU), it could diminish the treatment’s efficiency and not guarantee adequate inactivation of microbes. If highly turbid water is the only source available, the suspended solids need to be removed, for example by (cloth) filtration, sedimentation or flocculation. The WATA® is appropriate for urban and rural areas and foster people’s autonomy where the technology is implemented. Since the WATA® devices need a reliable electricity supply to operate, the Mini-WATA®, WATA-Standard® and the WATA-Plus® are designed to be easily powered with solar energy.

Sodium Hypochlorite Production

The user first prepares salt water at 25g NACl/Liter. The WATA® device needs to be immersed in the salt water and connected to a reliable source of electricity. The salt water is converted into sodium hypochlorite solution with a 6 g/L concentration of active chlorine through a process known as electrolysis. Potentially contaminated water can be made potable by adding a small dose of chlorine (5 mL chlorine per 20 L water). Despite the simplicity of operating a WATA® device, the production of active chlorine and disinfection of potable water for a community is a responsibility, and thus requires skilled people as operators, specially trained and dedicated for that purpose.


Production of Chlorine using the WATA-Standard®

Production of Chlorine using the WATA-Standard®

WataTest® and WataBlue® reagents are part of the WATA® kits and allow the user simple onsite water quality control. WataTest® and WataBlue® are non-toxic and inexpensive reagents which are used to measure the active chlorine concentration of sodium hypochlorite and free residual chlorine in the water, respectively. Free residual chlorine (FRC) is important because sufficient levels are required to ensure adequate inactivation of microbes and to guarantee the residual effect that chlorine has of preventing the recontamination of water during handling or consumption. Since increasing levels of FRC makes the water taste and smell unappealing, the WHO recommends a level of FRC between 0.2 and 0.5 ppm in order to strike a balance between disinfection and water taste and smell. 0.5 ppm is the level of FRC that the WHO recommends as striking the balance between effective disinfection and acceptability in terms of taste and smell. The. WataBlue® allows the user to carry out a safe and systematic quality control of the treated drinking water to ensure that this level is reached.

 Tinkisso employees in Guinea, Conakry. Tinkisso produces sodium hypochlorite solution using WATA® devices and then stabilizes and bottles the solution for sale throughout Guinea.

Tinkisso employees in Guinea, Conakry. Tinkisso produces sodium hypochlorite solution using WATA® devices and then stabilizes and bottles the solution for sale throughout Guinea. 


Devices need to be rinsed after each procedure with clean water. If after several uses you notice white marks on the WATA®, prepare a solution of 50% white vinegar (or lemon juice) and 50% clean water. For the Mini-WATA® and WATA-Standard®, leave the device to soak for several hours (overnight for example) and then rinse it with clear water. Never scrub the titanium plates. WATA-Plus®, Midi-WATA® and Maxi-WATA® need to be soaked for at least 24 hours and be completely immersed in the 6 – 10 L solution.


Properly used, well maintained and carefully stored after each use, WATA® devices are designed to operate for 10,000 operating hours, or around 5 years of use. Active chlorine is very sensitive to light. It is therefore very important to store the solution produced with the WATA® devices in closed and opaque, non-metallic recipients and label it with the production date. Place the container in a cool place, out of reach of children. Do not expose it to sunlight. The sodium hypochlorite should be used within 24 hours as the concentration of active chlorine will decline if the solution is not stabilized.

WATA® Application and Business Models

Our objective is to make safe water treatment a profitable activity for communities of developing countries. In the long run, the production and sale of chlorine should create an income generating activity for the local population and ensure their independence in water treatment. The cost for one litre of active chlorine concentrate stands at US$ 0.06.

WATA® is more than a device, it can be combined with health education, technical training, and the creation of an economic model based on sodium hypochlorite and chlorinated water production and sales. Making safe water treatment a profitable activity while insuring autonomy.

Several dissemination models have been tested and approved in the field:

  • Through health centres: The WATA® device can produce, at a very low-cost, the large quantity of quality disinfectant needed to ensure hygiene standards in health facilities. This reduces nosocomial diseases and decreases mortality during childbirth. In addition, the sodium hypochlorite solution can be used as an effective, low-cost wound disinfectant (Dakin’s solution).
  • Through economic structures (i.e. women’s groups, salesperson in kiosks, pharmacies): Direct chlorine sales or disinfection of drinking water, with subsequent sale at kiosks or home delivery, using the chlorine produced by the WATA® device creates an income-generating activity;
  • Through school structures: One WATA® device can ensure that the school’s supply of drinking water is disinfected and be a source of disinfectants to clean floors, surfaces and latrines. They also create an opportunity for promotional and awareness activities around the themes of safe drinking water and sanitation;
  • Through water user associations and water utilities: As an autonomous chlorine generator, the WATA® device can substitute for other chlorinated products in regions where chlorine gases and powders are under embargo, as in armed conflict areas.

To appropriately implement WATA® devices in your specific environment it is recommended to design and test the implementation, pilot it together with the users and customers, adapt and amend the dissemination strategy and the respective business model in order to scale-up and replicate the successful approaches that have been pioneered with the WATA® devices.

Library references

Safely managed drinking water - thematic report on drinking water 2017

The Joint Monitoring Programme (JMP) for Water Supply and Sanitation’s report examines the SDG vision for universal access to water and sanitation. New ‘ladders’ for monitoring drinking water services at home, at school and in health facilities are presented, together with proposals for enhanced monitoring of inequalities and affordability in order to progressive elimination of inequalities and global progress towards SDG target 6.1.

WHO ; (2017): Geneva: World Health Organisation URL [Accessed: 25.07.2017]

International Scheme to Evaluate Household Water Treatment Technologies

WHO established the international scheme to evaluate HWTS. The Scheme aims to consistently and independently evaluate the performance of HWTS against WHO performance recommendations. The report provides the result of these assessments from a range of HWT technologies including solar, chemical, filtration and ultraviolet (UV). It highlights that of the ten HWT products evaluated, eight were found to meet WHO performance recommendations. The report also recommends specific actions at the national level needed to ensure that health gains from HWT are realized, including strengthening regulation and evaluation of HWTS.

WHO ; (2016): Geneva: World Health Organisation URL [Accessed: 07.04.2017]

Antenna Foundation – Water & Hygiene

Antenna Foundation, a Geneva-based Swiss Foundation dedicated to develop and disseminate technologies for essential needs of the most vulnerable people around the world, presents its activities including the WATA® devices and provides the reader with background information about safe water and hygiene.

ANTENNA FOUNDATION ; (2017): Geneva: Antenna Foundation URL [Accessed: 10.08.2017]
Further Readings


Powerpoint presentation of the water purification system implied by AUTARCON. This system uses solar energy to realise mechanical filtration and chlorification of water.

AUTARCON ; (2012): SolarPV Driven-Drinking Water Treatment. Munich:

Filtration & Chlorination Systems

Introduction to filtration and chlorination systems at the household level.

CDC/USAID (2009): (= CDC Household Water Treatment Options in Developing Countries Factsheets ). New York: Center for Disease Control and Prevention (CDC) and United States Agency for International Development (USAID) URL [Accessed: 01.04.2010]

Scaling Up Household Water Treatment Among Low-Income Populations

This report examines the evidence to date regarding the scalability of HWTS. It seeks to consolidate existing knowledge and experience and distil the lessons learnt. Its primary aims are to 1) review the development and evolution of leading household water treatment technologies in their efforts to achieve scale, 2) identify the main constraints that they have encountered and 3) recommend ways forward.

CLASEN, T.D. ; (2009): (PhD Thesis). Geneva: World Health Organization (WHO) URL [Accessed: 09.04.2010]

Household water treatment and safe storage in emergencies

This document is intended as a general manual on household water treatment and storage in emergencies. Methods of treatment but also promotion are presented, including factsheets, a decision tree and very comprehensive illustrations.

IFRC (2008): pdf presentation. Geneva: International Federation of Red Cross and Red Crescent Societies (IFRC) URL [Accessed: 23.04.2012]

Smart Disinfection Solutions

This booklet, part of the Smart Water Solutions series provides a wide range of methods and products for home water treatment in rural areas.

NWP (2010): Examples of small-scale disinfection products for safe drinking water. (= Smart water solutions ). Amsterdam: KIT Publishers URL [Accessed: 07.07.2010]

Water, sanitation and Hygiene interventions to combat childhood diarrhoea in developing countries

This document provides a review of the effectiveness of interventions in the water, sanitation and hygiene (WASH) sector in promoting better health outcomes in developing countries, as measured by the incidence of diarrhoea among children.

WADDINGTON, H. ; SNILSTEIT, B. ; WHITE, H. ; FEWTRELL, L. ; (2009): (= Synthetic review, 001 ). New Delhi: International initiative for Impact Evaluation (3IE) URL [Accessed: 07.06.2010]

Guidelines for Drinking-water Quality, Fourth Edition

This volume of the Guidelines for Drinking-water Quality explains requirements to ensure drinking-water safety, including minimum procedures and specific guideline values, and how those requirements are intended to be used. The volume also describes the approaches used in deriving the guidelines, including guideline values. It includes fact sheets on significant microbial and chemical hazards.

WHO (2011): Geneva: World Health Organization (WHO) URL [Accessed: 08.08.2011]

Drinking water chlorination

This 8-pages information paper highlights chlorine’s critical role in providing safe drinking water; the potential health and environmental effects of chlorine and disinfection by-products; and considerations for selecting disinfection methods.

WORLD CHLORINE COUNCIL (2008): Position Paper URL [Accessed: 07.06.2010]

Conservation et Traitement de l Eau a Domicile

This practical guide provides a review of different processing techniques and adequate water conservation at home and is structured around 10 key questions that should be posed before choosing a suitable solution.

DESILLE, D. ; (2013): Paris: Programme Solidarite Eau (PSeau) URL [Accessed: 06.06.2013]

Antenna Foundation – Water & Hygiene

Antenna Foundation, a Geneva-based Swiss Foundation dedicated to develop and disseminate technologies for essential needs of the most vulnerable people around the world, presents its activities including the WATA® devices and provides the reader with background information about safe water and hygiene.

ANTENNA FOUNDATION ; (2017): Geneva: Antenna Foundation URL [Accessed: 10.08.2017]

Range of WATA® Devices

The instruction sheet provides detailed information of how to install and use the WATA® devices in different contexts. It highlights precautions to be made and provides additional information about the production and use of sodium hypochlorite.

ANTENNA FOUNDATION ; (2017): Geneva: Antenna Foundation URL [Accessed: 10.08.2017]

Range of WATA® Devices - FAQ

This link presents the frequently asked questions (FAQs) and answers on the installation, use and maintenance of WATA® devices as well as the different applications of active chlorine. It has been prepared and complied by Antenna Foundation.

ANTENNA FOUNDATION ; (2017): Geneva: Antenna Foundation URL [Accessed: 10.08.2017]
Case Studies

Alternative Versions to

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