A central problem with my proposal — some water for free, pay for more — is that it’s based on a per capita allocation of water. Since most water utilities do not know how many people live at a given meter, it’s hard to establish per capita allocations and pricing.

I was talking to some Australians who mentioned that their water bills show their use and gave a calculation of per capita consumption as if they had 2, 3 or 4 people in the household.

This calculation helps people understand how well they are doing at pursuing a target of 155 liters/capita/day (41 gallons/c/d). They are currently at 174 lcd.

Now it’s clear that any water district can use this method to help their customers help themselves,* but it can be leveraged for use in a per capita allocation/billing system, if you add a little twist.

So here’s how it works:

1. Ask people to declare the number of people at their address (meter).
2. Allocate some cheap water for each individual, and then charge more for use above that use; see this post for more.
3. Give them a bill that shows their use per individual, given the number of people they have declared.
4. (The twist) Also give them the use, number of people, and use per capita for 10-20 neighbors around them. This latter bit of information will create a common knowledge of how many are using how much, which will put pressure (social pressure) to both reduce overall consumption as well as honestly declare the number of household members. Although some people may complain that it’s invasive, I do not agree. Most water conservation campaigns focus on “doing your part for the community,” and most people do not mind their neighbors knowing how many people live in the house.

Bottom Line: Water conservation takes effort, and we need to be given reasons to exert it — financial and social incentives provide good reasons.