Showing bacteria in contaminated water

Dear all

During the awareness campaign in India about the importance of safe drinking, many village women expressed a need to see bacteria that are present in contaminated water. This seems to be very important to them. They have to see, in order to believe.
We are lloking for a way to make this possible.
Using a microscope it is nearly impossible to let people see bacteria that are presnt in the water. You will need huge concentrations of bacteria to be able to show this, much higher levels than can be found in practice.
Showing bacteria multiplication on agar-agar plates, colour change, or other comparable methods do not seem to work.
Does somebody have ideas or suggestions regarding this subject?

Klaas van der Ven
Basic Water Needs Foundation
watersafe@hetnet.nl