Finding a Leak

[Sugaree]

So, we've got a slow leak (or three) somewhere.  My house is really old, so we've been playing whack-a-mole with plumbing leaks for awhile now.  We have water detectors under all the sinks and the water heater and it doesn't seem to be there.  We're also not seeing anything under the house or any soft spots in the yard between the meter and the house.  Where else should I be looking?

[BudgetSlasher]

I am confused, why do you think you have a leak? Everything you said seems to indicate that you have no evidence of a leak.

[Sugaree]

I am confused, why do you think you have a leak? Everything you said seems to indicate that you have no evidence of a leak.

Because we used 3600 gallons in November and 6300 in December and I can't pinpoint anything behavior-wise that would explain it.

[techwiz]

I would recommend checking for a running toilet https://www.wikihow.com/Fix-a-Running-Toilet, and outside hoses those are two places which can leak undetected. 

[Sugaree]

I would recommend checking for a running toilet https://www.wikihow.com/Fix-a-Running-Toilet, and outside hoses those are two places which can leak undetected.

Thanks!  I did the food coloring in the toilet tank thing a few months back, but it's worth checking again.  The hoses are something that I've never thought to check. 

[Uturn]

Turn off the water at the street, then watch the meter.  If it shows flow, you have a leak somewhere. If you have a shutoff for your whole house, turn that off. If your meter still shows flow, it is between the street and house. If the second test passes, then you need to turn the valve inside the house back on and go check every faucet, toilet, and hose bib.  Don't forget the clothes and dishwashers. 

[Greystache]

Do you have sprinklers for your lawn/garden? I had a similar problem recently and that is where I found the leak. One of the sprinkler valves was defective.

[sonofsven]

If you're not seeing water  anywhere in your house then the problem is likely in the line from the street to the house, unless your toilets are running (seems you would have noticed that).
Do you have a basement or crawl space? If crawl space have you looked there? If basement do you have an old floor drain? Sometimes the p trap has a small water line that keeps the trap from drying out (to stop the "swamp gas" smell from seeping in).
Most likely though it's in your main, especially if it's old.
Has anyone been doing any street maintenance, or digging for sewer line repairs, anything like that?
I've seen big leaks go for months with no visible water on the ground.

[Sugaree]

My husband got in the crawlspace yesterday and said he didn't see anything.  We did have a leak under there back over the summer, but fixed that one.  I'm going to check the toilets again, because everything points to it being something there. 

[Model96]

I think you are onto it with the toilets. Also check the hot water tank if you have one, the relief valve may be leaky, which will send your water and power expenses sky high!
When there is no water being used in the house, check the meter to see if it is still turning.....if it is you definitely have a leak somewhere. Hopefully it isn't underground as previously mentioned.

[BudgetSlasher]

I am confused, why do you think you have a leak? Everything you said seems to indicate that you have no evidence of a leak.

Because we used 3600 gallons in November and 6300 in December and I can't pinpoint anything behavior-wise that would explain it.

Are both of those abnormally high based on you historical use spanning a longer time period? I cannot say I know what ours is as we are on a well (the only indication of use is a 2-3AM water softener recharge), but I googled and the first few seems to say the average US house is 300 gallons a day and another says the average per person household use is 3,000 a month.

If this is out of line of historical use and since you have a history of leaks the first thing I would do is pick an extended period of non-use of water (vacation, everyone sleeping, everyone at work/school) and read the meter before and after a period of non-use; if there is a difference you have use.

Presuming the answer is yes.

First if you have shut off at the house, and do the same test. If the meter keep spinning then you have a leak b/t the meter in the house.

Then I would start shutting things off (I can shut off entire bathrooms and all individual fixtures) and do the same test. I probably would start with toilets, outside hose bibs, and items that are generally out of site and out of mind. Do you have any floor drains that might have an automatic trap primer?

If you've shut off all the fixtures one by one and still have consumption, I would do the test will all the fixtures turned off. If you have consumption still you might have a leak in a pipe somewhere in the walls (that will be harder to find). I had a leak drip in the basement after taking a long shower ... turns out someone put a drywall screw through the pipe between the showerhead and valve and over the years it had rusted away to the point where the leak was noticeable.

[WSUCoug1994]

I think you are onto it with the toilets. Also check the hot water tank if you have one, the relief valve may be leaky, which will send your water and power expenses sky high!
When there is no water being used in the house, check the meter to see if it is still turning.....if it is you definitely have a leak somewhere. Hopefully it isn't underground as previously mentioned.

This happened to us - lost a lot of water and propane until we figured it out.

If you have them, sprinkler/drip line solenoids can cause a lot of leakage.  One tiny pebble/debris in that seal can leak a lot of water that is hard to locate.

[habanero]

I think if you had a almost 3000 gallon leak in a month inside the house you would most likely notice it. That's a lot of water.

[Sugaree]

I think we may have narrowed it down to one of the toilets.  After I posted this, I started looking and found that one of them had just the slightest hint of a ripple in the bowl even after sitting for awhile after being flushed.  It wasn't enough to make the little triangle on the meter noticeably move though.   My husband replaced some seals or gaskets or something in it yesterday. So we'll see. 

[techwiz]

I think we may have narrowed it down to one of the toilets.  After I posted this, I started looking and found that one of them had just the slightest hint of a ripple in the bowl even after sitting for awhile after being flushed.  It wasn't enough to make the little triangle on the meter noticeably move though.   My husband replaced some seals or gaskets or something in it yesterday. So we'll see.

Excellent, hope you solved your issue.  I had a toilet with a leaking flapper(which didn't make a noticeable running sound) it can waste a bunch of water. It took an unpleasant change to our water bill before we went looking.