Chulli Description

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Credit: Richard Johnston, UNICEF

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Credit: Richard Johnston, UNICEF


A simple flow-throught system which uses wasted heat generated in traditional clay ovens (chullis) to pasteurize microbiological–contaminated water.

Rajshahi University and United Nations Children's Fund


Amount of Water Treated
The Chulli Water-treatment system produces up to 90 litres of hot pasteurized water per day at the household level, without any additional time or fuel required.

Contaminant Removal
Laboratory testing, along with over 400 field tests on Chulli systems deployed in six pilot villages, showed that the treatment completely inactivated thermololerant coliforms.

Ease of Use
The simple technology, occupying almost no extra space in the household, fascinated people. Many families were astonished by the large amount of water produced and even complained that the system produced more treated water than they could conveniently store.

Benefits and Drawbacks

  • Inexpensive
  • This device may be built with off-the-shelf parts available throughout most countries.
  • Large quantities of hot pasteurized water can be obtained quickly.
  • Pasteurization does not improve chemical quality, so surface water containing industrial or chemical contamination should not be used for the Chulli Water-treatment system.
Ideal Situation
Where groundwater is contaminated with arsenic (or fluoride), the Chulli Water-treatment system may provide a good alternative, if acceptable sources of surface water are available. However, the Chulli system has the potential for broader application. Millions of people throughout the developing world are using microbiological-contaminated drinking-water, which could be made safe through this flow through pasteurization process. The Chulli technology present a new opportunity for low-cost, effective treatment of water at the household level.


The Chulli Water-treatment system is inexpensive (costing about $6.00 US) and requires no operating and maintenance expenses.



Contact Information

Richard B. Johnston
Water and Environmental Sanitation Section
United Nations Children's Fund
BSL Office Complex, 1 Minto Road,
Dhaka 1000, Bangladesh
Email: rjohnston [at] unicef [dot] org