Overview of the NUF500

It is important to explain how water, highly contaminated by bacteria, viruses, and protozoa, can be collected and processed easily into safe drinkable water on a useful scale without using electricity/external power. 

How Does the Device Work?

Some years ago, while working in Israel on a nephrology/dialysis project, we were informed that a company in Tel Aviv had developed a process in which sterilized, previously used polysulfone hollow fiber hemodialysis dialyzers (filters), were being employed for the purification of sewage water for subsequent crop irrigation, etc.  Laboratory testing had revealed that the product water was completely free of any bacterial and viral contamination. The system at that time was of industrial size, comprising about 450 polysulfone filters, utilizing electricity to power the pumping of sewage water through the filters. 

In our context, the question was asked as to whether this apparatus could be downsized significantly and function with a foot or hand pump, rather than requiring a power source.  Within 18 months a device (NUF500) with 8 polysulfone filters, powered by hand pumping and producing enough drinking water for a village has become available.  Dr. Mino Negrin,Chief Executive of NUFiltration Ltd, Caesarea, Israel is responsible for this development. Subsequently Theophilus Ocansey, a Ghanaian working on the Easy Water project since its inception developed the gravity flow concept which eliminates hand pumping altogether.  Most sites are now running with gravity flow rather than manual pumping.

Pure water in a volume of 500L/hour can be pumped manually, with half that rate attained with gravity flow.  We have worked with the manufacturers to organize transport of the devices and have on site a small inventory of replacement parts for the devices in each site.  The most important features of this device are that the hollow fibers ordinarily used to filter toxins blood in patients with kidney failure now filter water so that there are no infectious agents left behind whatsoever.

In the past two years of experience with potential site installations in Ghana, the question is not if the water sources had been “improved” but whether these “improved” sources were free of contamination after the “improvement”.   It is an important part of our routine that we test all potential water sources prior to initiation of our device All have been contaminated, even if they were declared an “improved” water source.  The NUF500 eliminates 100% of the contamination.

NUF500 Device Specifications:


No external power requirements at all. Only human pumping needed to force contaminated water through the filter (it requires little force) or, as indicated earlier a gravity feed system which requires an additional amount of up front capital for a 1000 L tank, supporting structure for height and a very small gasoline pump.  Regular “backwash” is required to clear filters of sediment.  Backwash procedure is done on site by just changing position of valves in the device itself without dismantling anything.  Duration of backwash is approximately 10-15 minutes.  Frequency depends on the raw water quality – from three times per day to once every hour.


  • Device total weight:  18 kilograms

  • Functioning parts:  pump handle

  • Passive parts:  8 used, sterilized hemodialysis filters and a pump diaphragm

  • Filtered substances: all components larger than 0.03µ: suspended solids, bacteria, viruses (at 6-7 LOG rejection rate), organic matter bigger than 0.03µ.

  • Pure water production/hour/device pumped manually:  8 liters/minute. Gravity driven about half that rate