Dedicated Irrigation Meter
In most homes the majority of water is used outside by the landscape, where overflow feeds into the storm drains. Indoor overflow (and wastes) feed into the sewage system. In houses with large landscapes, it makes sense to measure the two uses separately. Here's why:
If you find a sudden spike in your water bill, you can find out right away, by reading your meters, whether it's from extra use indoors or extra outdoors. You'll have half the area to check.
Since sewage charges are calculated from all meter readings, except dedicated irrigation meters, you may be paying too much. Check to see how sewage is billed. If it's billed by a flat charge, you're ok. If it's billed by the amount used, you may be paying sewage charges you don't owe.
Once a dedicated meter is installed, check the main meter (called a mixed meter) to see how much water you normally use per month for indoor use. That's the only thing sewage should be billed on - for maintaining the public sewage system. Multiply that amount by the sewer rate charged by your water provider. If you have been paying more than that each month, the water provider owes you money.
Some water suppliers will refund the homeowner for prior overcharges, so install the meter first, do your checks, then call them.
Irrigation System Troubleshooting
The following instructions presuppose that you have a dedicated meter. If not, you can still use your house's mixed-use meter to run this check. Just make sure that all water is turned off before starting, inside and out.
Set aside a day to turn off the irrigation system and go through some checks. Find your water shutoff valve - somewhere between the house and street - and turn it off. Give it about twenty minutes for water in the system to stop flowing. Now check your meter. Is it still running? Is the leak indicator triangle or circle showing? If yes, you have a leak.
Now it's time to find out where that leak is. The procedure is to check the irrigation controller, then the valves, then the sprinklers. If you still haven't found it, then you'll check for underground piping leaks, for which you may want to purchase equipment. For the initial checks, all you will need is:
Paper and pencil
A slew of irrigation flags (small, bright, triangular flags hooked to a 6" thin metal rod that you stick in the ground)