[jcrawfordor]

Well, most of the efficiency analysis of water systems relies on meters in some way. This makes fairly intuitive sense... if you don't have any tracking of what you actually deliver to the end-user, it's hard to know what the actual in-out balance of the system is. For example, one of the most important operational metrics for municipal water systems is the non-revenue water portion. This is the difference between flow out of the water treatment plant and cumulative meter readings---and it indicates water that is lost in several different ways, most significantly (in most cases) leakage throughout the distribution system. This can be very substantial, as much as 30% in poorly maintained systems. I see an article estimating the non-revenue water in Sacramento at 10%, which is not terrible but still higher than many well-run water systems. But what's really problematic is that a spokesperson for the water department emphasized that this is a rough estimate because of the lack of meters on about half of their user connections.

The lack of meters makes it basically impossible to perform a "water audit," a best practice for water utilities that helps to quantify and---more importantly---locate leakage and equipment problems that lead to non-revenue water. It makes reducing the non-revenue portion very difficult since there is no real accounting of where losses occur. This makes costs higher for everyone, and also means that some of the water extracted from the river is taking an uncertain return path that greatly increases risk of contamination by urban pollutants in the vadose zone. It also makes it difficult to quantify some non-return dispositions of water like evaporation, not only for the utility but for customers.

Indeed, the 10% estimate they are producing right now is based on modeling of river extraction and return rates and aquifer levels. So they are basically trying to estimate their non-revenue based on the difference between what they take out of the river and what they put back in, but that is very difficult and gives little information on where the actual problems are.