Cannot find leak, but my water bill has skyrocketed.
 

For about nine years our water bill ran a pretty steady $55/mo. I think $25 of that is trash and recycling pickup. It's cheap in the desert. In the last year it's crept up to $78/mo. I drained and refilled my 10k gal. pool in April, 2020. No spike in bill then, so I figured they were staggering it over the next 12 mos. It was $78 last month and the current bill is $211. We were traveling for 10 days of the last billing cycle.

So I just shut off at the meter at the end of the driveway, took a reading, waited 20 min and checked again. No change. WTF is this water usage coming from? What to check next?

Leak in the main line from the meter to the house?

I didn't shut off the service line at the hose bib by the front of the house. I shut down the main at the meter. Wouldn't any leak downstream of that cause the meter to move?

It means the leak (if there is one) is between the meter and your house.

Does the meter move when all water is shut off in the house.

Logically I would think so. Maybe the WC made a mistake. Do you have access to their copy of the meter reading?

I had everything shut down. How would a leak between the main and service lines not make the meter move when water is shut off at the meter? Wouldn't there be a wet spot somewhere in the yard or driveway too?

Probably a toilet.

Turn on the meter, and don't use anything in the house, does the meter move?

To check a toilet, turn off the valve at the toilet, and see if the tank drains.

No because the meter already accounted for the water moving through it so if you shut it off and the leak is after that then it's just emptying the water out of the pipes stored in the pipes.

Try shutting off the service line at the house and leaving the meter on at the street and see if it's still running. That should confirm the leak is between the meter at the end of the driveway and the house.

I will try that tomorrow. We have two toilets. One works like a champ, one almost never goes down all the way and still take forever to refill. I had a plumber out in June for that one and he couldn't figure it out. I changed the cartridge before calling him and he got it to work just a little better, but still not right. Never hear it running when not after a flush though.

Or read the meter before going to bed and first thing in the morning. If you need the toilet during the night, shut it off. You can use each toilet once with no water supply.

It's Sep. I assume like here, Sep is still "summer hot" and summer hot there is ridiculous. My one visit to AZ, it was so hot and so dry that I could see you having a leak that didn't show up as a wet spot.

Is it possible that they don't read the meter every month, and they just happened to read it and caught up a deficit after you refilled your pool?

^^^ This.
Had a power outage a couple weeks ago....water well system.
Thought there would be water to flush the toilet one time....nope...dry.
The flapper was leaking continually and the water was gone.

Fixed the flapper and the water pump runs half as much as before.

You can buy a non-staining dye that you put in the tank. Don't use one toilet. See if the water in the bowl has the dye color in it after a day. Then do the other one. That much increase usually means the water service line between the meter and the house has a small leak underground. Because it is a high pressure line it will run a huge bill quickly.

When our bill went from about $40 to $200 - it was a water leak in an outside line that runs to the chicken coop. It was leaking about 100 gallons/day. Sounds like your leak is way bigger than a leaking flap valve on a toilet.

Your test is flawed.

For water to flow, you need pressure to drive it.

When you shut off the master supply valve, the pressure in your system may bleed off due to a leak but since water is basically incompressible, if it bleeds down a pint, your pressure is bled off and there will be no further leakage (unless there is a leak at a low point). If you have a pressure tank in your system, the pressure tank volume needs to bleed down too.

Some thoughts and leaks i've fixed
 

Most likely, it is the toilet(s). I just had a water billl go from $60 to $175. I found a flapper held open by a link in the pull chain. This can be an intermittant "leak". Get rid of any excess chain length.

I've had the city, (water company) forgive a huge water bill for a leak i doccumented and fixed for a client - worth checking. They may do that only once a year or not at all. Still worth asking once you've got it fixed.

I cannot count the old worn out flapper valves i've replaced. It needs to be clean and supple. As above, get rid of any escess chain that might foul the closure of the valve. To improve the water flow, try the "Corky" flapper valve with a yellow foam float on the chain. This float prevents premature closure and allows more water into the bowl.

If the toilet water valve isn't shutting off completely, the water level will rise to the top of the "stand pipe" in the tank, then overflow down into the bowl. This may or may not make enough noise to hear, but it is worth checking. If close to the top, adjust the float down a bit, then recheck.

If you have a big place, check all of your out buildings/faucets. Seen it happen.

If you shut off the valve where the water enters your house, but the meter is still turning, then the leak is between the meter and that valve - fixed a few of those

Lastly, if your toilets and hose bibs are all ok, you need to check the hot and cold water supply pipes, (where accessible). I've fixed pin hole leaks in copper pipes under the house and in the attic, as well as rusted through galvanized iron pipes and broken plastic pipes.

Good luck,
chris

My buddy Rich who has a house in Palm Springs had a similar mystery. Turns out that while he was out of town the neighbor ran a hose over the wall to Rich's spigot and used that to refill his pool . . . .

A while back, I noticed the gutter in front of the house was wet with water flowing for a few days straight and I traced it back to the drain from my back yard.
That didn't make sense because everything in the back yard was dry.

Further investigation revealed the culprit:

My pool has an automatic fill valve, and the plastic float had cracked and partially filled with water.

That raised the level in the pool slightly. When the built the pool they didn't give that level setting much room for variance and that extra half inch was enough to reach the over-flow drain, which was connected to the drains in the yard.
The pool valve kept trying to raise the level by adding water, which went right out the drain to the street.
I replaced the float valve (under $20), reset the level a little lower, problem solved.

If I had not noticed the water in the gutter out front I would have kept dumping water into the street for a lot longer than just a few days.

Jesus! And Palm Springs yet...

I remember one of someone figuring out a suddenly high water bill. Seems their cat had learned how to flush a toilet and loved doing so...

My pool leveling valve is shut off. The float in there always gets hung up on weeds or debris in there, so I just manually refill a few inches every few weeks. I replaced the MB toilet today with a good one. Plumber can't come out to check things until tomorrow.