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There will be two type of Sipper or pit life extender tested.

The first is a simple displacement pump without any form of membrane and where the outlet of the pump discharges directly into a soak away, so as to prevent any waste being dumped near the house. The aim is to test the market and see if HH would buy such a product.

The second will contain the membrane and this is where compromises will have to be made. The most likely would be micro membranes with the larger pores which would stop the bacteria, but not the viruses. These are cheap and durable and the main issue may be the surface area of membrane needed to achieve the required water discharge rates and how to clear the membrane fouling. Ultra filtration removes viruses, but likely to require power and a cross flow approach to make it work. This makes it more complicated and more expansive, but there may be market with richer HH living in higher rise blocks.

We do not want to get burdened by the need to producer a discharge of drinking water quality - this is where the Gates Foundation seem to be getting stuck. Apparently even conventional treatment plants are not effective in removing viruses and they are hard to detect using simple tests.

The moral question is perhaps around the poor have higher standard imposed on them than the rich. Also - the one step at a time is a better approach.

There will be two type of Sipper or pit life extender tested.

The first is a simple displacement pump without any form of membrane and where the outlet of the pump discharges directly into a soak away, so as to prevent any waste being dumped near the house. The aim is to test the market and see if HH would buy such a product.

The second will contain the membrane and this is where compromises will have to be made. The most likely would be micro membranes with the larger pores which would stop the bacteria, but not the viruses. These are cheap and durable and the main issue may be the surface area of membrane needed to achieve the required water discharge rates and how to clear the membrane fouling. Ultra filtration removes viruses, but likely to require power and a cross flow approach to make it work. This makes it more complicated and more expansive, but there may be market with richer HH living in higher rise blocks.

We do not want to get burdened by the need to producer a discharge of drinking water quality - this is where the Gates Foundation seem to be getting stuck. Apparently even conventional treatment plants are not effective in removing viruses and they are hard to detect using simple tests.

The moral question is perhaps around the poor have higher standard imposed on them than the rich. Also - the one step at a time is a better approach.