In principle, this could be done easily. We have, here, pre-paid electricity meters & I saw in Great Britain pre-paid gas meters. The trouble is: inhabitants of a house may sleep in the dark with no TV when points, stored on electricity card, are over & they can wear heavy clothes or do not cook when the points, stored on the gas card, are consumed but it will be a severe hardship if this is applied to water. I hope that pre-paid water meters are never used. 

It is possible, of course, and it is reality of use of prepaid water meters in many countries dear @Taratisio! Furthermore, in Serbia, there is an intention for MULTI‐UTILITY METERING! "Meter possesses an electrical interface (M‐Bus) for connection of other metering devices located with the electricity customer. In general, these include, water meter, gas meter and heat meter. Meter minimally possesses memory registers for accounting data storage for each of the above‐specified meters. Storage capacity is 12 accounting periods for each of the meters!"

http://www.eps.rs/Eng/Documents/FUNCTIONAL%20REQUIREMENTS%20AND%20TECHNICAL%20SPECIFICATIONS%20OF%20AMI-MDM%20SYSTEM.pdf

Why Should Water Utilities Move to Smart Metering? "As drought and population growth sharpen the focus on water, utilities, environmental groups, and governments increasingly look to smart metering to help customers better understand and curb their water use; to identify leaks; and to underpin new rate and regulatory programs that respond to community water needs...Justifying the implementation of the technology to support smart metering, however, will require cooperation and support from local and regional governments, communities, and above all, customers...A strong technology infrastructure can help water utilities realize their new vision. But creating such an infrastructure is no easy task. To respond to these challenges cost-effectively, water utilities should consider implementing an integrated infrastructure of business software applications. With a solid applications infrastructure — especially one optimized for water utility business processes — they maximize their opportunities to meet their most important goals: matching water supply and demand at affordable prices that preserve communities and foster economic growth."

http://www.waterworld.com/articles/wum/articles/2010/01/getting-to-know-h2o.html

Thank you guys for the information.

Since the amount of flow can be quantified in the way electricity can be quantified infact both in parallel and series form, then it is possible to adopt metering device for water consumption too.

Yes that is possible. Ownership of the water supply scheme must be with community organizations of the region. Then they are responsible to look after the source areas and avoid any form of pollution.

In India we have post-paid electricity and water meters. It is a good concept to have pre-paid water meters, a facility that is available for mobile phones now.

Best wishes.

Dear Friends as @B.R. Rajeswara Rao  mentioned here in India we have post paid water meter but as @Dr. Nizar Matar  mentioned that " I hope that pre-paid water meters are never used" I go with him on this issue. At-least clean drinking water must be available to every one I hope.

Something more on prepaid type of water meters! "...Prepaid  Water Meter is an example of a ‘water management device’ or ‘prepaid meter’. Prepaid meters have been installed by municipalities and other water providers in many parts of Africa since the 1990s. These meters can be programmed to release set amounts of water to control daily consumption. Prepaid meters are so-called because they require prepayment by the user, who can access water up to their credit limit using an electronic tag...."

http://www.hildiseastafrica.com/pre-paid-and-post-paid-water-meters/

http://en.wikipedia.org/wiki/Water_metering

As my colleagues from India rightly said, we have post paid water and electricity facility for rural as well as urban population. Now in urban area we are going for prepayment for electric supply which have not been opted by many people. The idea is good for supply of clean metered water on prepaid basis will control misuse of water. The other problem in the developing countries like India, in rural area even during rainy season to get clean water is difficult . In summer to get water is difficult and if these people get assured clean water on prepaid basis, they will be happy. 

thank you guys for your answers.

Well, I think it is possible though it also depends on the service provider. Things are often done differently in different countries. As long as we can measure the flow and volume of water that is consumed at a specific time and place. However, there are implications and challenges for this as we do have them with pre-paid electricity.

Of course,It is possible. And it could be done easily

Please Hatef,  tel me how this can be done, thanks.

Thanks guys for that