The numbers are final. San Diego county residents must reduce our water use by 8 percent to 10 percent, San Diego Water Department Deputy Director Michael Bresnahan announced at a pubic briefing last night.

So the city - like much of So Cal - will stay with its limited watering days plan, on the belief that restricting watering will do the trick. See www.sandiego.gov/water/conservation for the rules.

And it will look to your neighbors to start the enforcement.

No one has been able to point to any studies or past experience that suggests that restricting watering to three days a week will work. But there seems to be a lot of confidence that this irrational-looking plan will cut water use.

Last week, San Diego Water Department Resources Manager Luis Generoso said the idea behind the limited days and times is to get people to look at their irrigation timers.The default setting on many times is 10 minutes a day, seven days a week, and older timers revert to default after power outages. So people who haven't looked in a while are probably watering like crazy. And moving off daytime watering means far less evaporation - even during June gloom.

Customers can expect a flyer explaining the water rules in the next bill. And they'll see another flyer - a plane over the beach with ‘Save Water' banners during the July 4th weekend.

What the water department won't be doing is looking at water bills for increases in use - except for the top 1,000 water-using households, which can expect some contact from the Water Department. A typical single-family household uses 14 HCF each month.

The city has moved five people from other departments to enforce the new rules - that's five for 275,000 water customers - and set up a tip hotline for people to call in suspicious watering activity - presumably their neighbors, employees and drivers reporting roadside geysers.

But there are enough exceptions to make turning in neighbors dicey - if we're ready to turn in our neighbors at all.

Are we ready for that? Aren't these the same neighbors we hope will call the fire department if they see flames and the police department if they hear screams? The ones who tolerate our barking dogs, even walking them when we've got family emergencies; hire our teens for yard work and babysitting; pick up our mail when we travel?

No one told them not to lay sod for a new lawn this year. Or to skip the fruit trees - hey, and thanks for the apples and avocados, neighbor!

We aren't going to go over and talk to them about their watering habits either. Not unless we want to hear about the noise we make into the night, the ugliness of our own landscaping and the half-finished fence they see every day.

Of course, we can call in reports on the landlords on our block (apologies to the conserving landlords). One of the basic rules for landlords renting houses is to pay the water bill because it's often the only way to find out about leaks and it keeps the landscape from dying as tenants try to save money. Landlords often use landscapers, whose mow -blow-and-go routine can mean no one looks at the irrigation timer.

Making assumptions about what people around us are doing is tricky. Some of our neighbors are following the rules but things still look like violations, like the homes using drip irrigation or the very modern weather-sensing timers that are allowed to run longer than 10 minutes. Some of those folks are pretty concerned about being turned in - and they're going to public meetings to ask about getting in trouble after they've made special efforts and they're saving water.

And people who've been obvious in our conservation efforts are afraid that our neighbors will think we turned them in.

With all this minding our neighbors business, wouldn't it be better to move towards a more rational plan that assumes water shortages are a long-term problem?

A plan that actually looks at water use and gives people credits, unrestricted rebates and tools - like the currently offline landscape watering calculator - to calculate and change their own water use?