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Mystery Leak

T

tab58

New member
We are struggling to identify a leak in our hot water system. This issue started on Feb 25 when our water utility installed a new Metron electronic meter on our service. Leak is between 20 and 70 gallons per day with lower leak rates at night?? Leak rates as high as 5 gallons per hour between 8am and 5pm. Our water usage has doubled with this 'new' leak. Water utility has replaced the meter three times. So far 3 plumbers and one thorough home inspector visit have found only 1 small leak in our 3/4" copper lines that was repaired. Crawl space allows easy and complete access to all service lines under the house and is semi enclosed showing any water leakage on that membrane. Thermal imaging indicates no water buildup in walls. We isolated toilets, washer, dishwasher, sinks and service line from the street. When we turn off the valve before the hot water heater(gas installed in 2023), the leak stops.Turning off the water heater does not stop the leak as we tested thermal expansion as a possible reason for the leak. No unusual connections such as irrigation system or water softener. We utilized a remote camera to search behind shower walls, and dishwasher to no avail. Used a stethoscope to try to identify water flow.
Leak is not constant but more of a cyclical wave pattern.
We are tracking our usage daily after measuring gallons used in shower and toilets. We were gone from the house one day this week and used some 50 gallons during that 9 hour period.
We are very frustrated and at a loss on what to do to identify the leak. Any suggestions on what we can do?
 
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Impressive diagnosis. Very unusual issue. Since the water is not showing up it must be going down a drain. Is there a way to monitor the drains?
 
Doc, great question. We checked the washing machine drain for a flow and put paper towels under sinks and showers with no activity. Dishwasher drain is pumped up and not active.Not sure how else to check drain flow except by unhooking each PVC drain in crawl space. Unfortunately I am unable to maneuver that area as I am recovering from shoulder surgery. I could try the stethoscope as my testing shows that a leak sounds very loud as I tested each sink and turned on the water to ensure I could hear the water flowing. What else would connect to a drain that I can not see?
 
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tab58 said:
When we turn off the valve before the hot water heater(gas installed in 2023), the leak stops
Click to expand...
Near the top of your hot water tank is a pressure relief valve. It'll look like the picture below.
Does yours have a pipe on it, pointing down that may go into a drain?
These valves are prone to leakage, even on newer units.
If your hot water tank is set to over 130°, that may make it leak even faster.

1745674491604.png
 
No ice make or humidifier. Pressure valve is not leaking. It would drain on the garage floor and no leak is showing. Toilets are not leaking, we did a dye test and also shutoff each toilet for an entire day, water in tank did not drop and leak was still indicated on Waterscope tracking. Very confused on why leak increases dramatically during the day and decreases at night. At night we see some hours with .17 gallons to .5 gallons per hour. During the day up to 5 gallons per hour. Also to reiterate, no leak showing when I shutoff water before the hot water heater indicating the leak is from a hot water line or the hot water heater. I also contacted water meter manufacturer, they accessed meter remotely and claim it was programmed and configured correctly.
Thanks for all of your suggestions.
 
That's strange. That's a fairly significant leak, would think it should be easy to find. Is there any other ways to isolate your hot water appliances?
 
Here's something that crossed my mind, is the leak happening while you're home or is it during the day when nobody is home? This might sound stupid, but is someone using your house while you're gone? Kids coming in to do laundry etc?
 
My first thought was the toilets are trickling steady. I see you eliminated the toilets but did you check the tanks to see if they are gummed up? Reason is that we're on a well. Last year our well kept kicking out like as if something was constantly running. We have 4 bathrooms. I inspected each toilet tank and they were all gummed up inside. I poured clr into each one and let them sit then scrubbed each tank clean. The only time our well kicks out now is when my son or daughter has an hour long shower in the middle of the night. Turns out one of the tanks had the slightest trickle from being gummed up with sludge. Just a thought.
 
Kelvar, leaking both when we are home and not home. I am able to shut off hot water appliances except for 2 showers and a tub. I am able to use a remote camera inside those wall cavities and they are completely dry.
 
Good thought on toilets, they are 2 years old and not leaking. Leak is in the hot water loop, I am able to isolate to only those lines and appliances. Really a head scratcher.
 
tab58 said:
Good thought on toilets, they are 2 years old and not leaking. Leak is in the hot water loop, I am able to isolate to only those lines and appliances. Really a head scratcher.
Click to expand...

That's why I thought toilets. We moved here in 2019. Changed out all 4 toilets in that time. Since then we've discovered a higher iron content in our water which was leaving an orange sludge in the toilet tanks.
 
This is certainly interesting! With it only being the hot water you have limited the possibility of it being only a few things. About all you can do is follow the hot lines and see what that shows you. It must be leaking in the perfect spot to run down a stud and making it's way into the ground somewhere. Could also feel the lines and see what is staying hot, might help lead to the problem.
 
What I don't understand is the spikes in the screen shot. I'd expect a leak to be a constant, low flow and not have spikes.

When no hot water is in use but the valve to the HW tank is open, do you see these spikes regularly (like day-to-day)?

Here's my current thought of a possible reason.
Your hot water tank may be leaking.
Do a thorough inspection of your hot water tank. Are there ANY signs of rust? If rust, the tank is leaking internally.
The spikes on your usage monitor may be the gas heating element kicking on thus expanding the water (and water pressure) forcing more water out of the tank. Depending on leak location, it may be sending the moisture out the gas exhaust or directly into the air so nothing visible as it's exiting as steam.
Take a look at this video. You can start around the 1:40 mark.

 
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bczoom said:
What I don't understand is the spikes in the screen shot. I'd expect a leak to be a constant, low flow and not have spikes.

When no hot water is in use but the valve to the HW tank is open, do you see these spikes regularly (like day-to-day)?

Here's my current thought of a possible reason.
You're hot water tank may be leaking.
Do a thorough inspection of your hot water tank. Are there ANY signs of rust? If rust, the tank is leaking internally.
The spikes on your usage monitor may be the gas heating element kicking on thus expanding the water (and water pressure) forcing more water out of the tank. Depending on leak location, it may be sending the moisture out the gas exhaust or directly into the air so nothing visible as it's exiting as steam.
Take a look at this video. You can start around the 1:40 mark.

Click to expand...
I tend to agree.
1) it is definitely not in the cold water side. Logic connects it to the installation of the new Hot water tank.
2) no visible evidence of water leak in either hot or cold system before this replacement.
3) I would suggest it may be an internal joint near the exchanger (burner heating coil) which sends the steam out the exhaust vent.
4) check the vent pipe above the roof for visible steam. Hold a cold piece of metal over the exhaust for condensation of steam. There will naturally be some but I betting it is heavy.
The exchanger would expand and contract with burner activity. Thus, the leak would be variable, but internal. And most severe when the burner is active.

If so, I recommend having the company that installed the unit, replace it.
 
Yes, checked the vent for steam. No rust evident anywhere on water heater. I turned the hot water heater to pilot yesterday and still saw leaks of 5 gallons per hour. The spikes on the screen shot are actual usage before we left house and after we returned. The cyclical line is the leak. Water heater installed December of 2023, no leaks until new meter was installed but....the cyclical usage did start when water heater was installed, no leak as the cyclical line was positive and negative equalling 0 usage. In other words, from Dec 23 until Feb 25, our water usage was about 50 gallons per day and no leak indicated. Now closing in on 100 gallons used per day and up to half of that is a leak. Old water heater did not have an expansion tank, new one does have an expansion tank. Do not have a 2 way valve to stop back flow from thermal expansion.
I thought that turning off the water heater would stop the thermal expansion cyclical flow, if that was the issue but that didn't happen so back to square one..
May have to shutoff water to hot water side when not needed until I can crawl under house and see for myself.
 
This is most likely something that is not complicated.
Given all the items you have so thoroughly checked.
Pipes in the crawlspace seems an evident concept.
The amount of water released is massive.
Something should be wet somewhere.
I know, I'm stating the obvious.

Query.
How cold did it get where you live last winter?
 
Might be rotten pipes from the street to the house. Had that happen at my house when we lived in town. We sold the house before we had a chance to fix it. We told the buyer what was wrong..... it still hasn't ever been repaired. That was 25 years ago. The house is a rental, now....... the landlord doesn't care.
 
I think I read something a long time ago about a similar situation. The problem turned out to be a kitchen faucet. Turns out, it was a single-lever type faucet, (a new install) and the hot water would leak through the faucet blender valve and back-track through the cold water pipe and leak out through the washing machine drain? ... (or the dish washer?)

I don't remember......... but have you replaced any faucet's, lately?
 
Don Coyote said:
Might be rotten pipes from the street to the house. Had that happen at my house when we lived in town. We sold the house before we had a chance to fix it. We told the buyer what was wrong..... it still hasn't ever been repaired. That was 25 years ago. The house is a rental, now....... the landlord doesn't care.
Click to expand...

I was just thinking the same thing. I used to own two houses back to back in a small town separated by a back laneway. The town water line ran down the back lane and being it was 80+ year old water lines in a muskeg swamp that went through extreme freeze and thaw cycles every year. As you can imagine the main lines would occasionally break. The town would come in and repair the main line but in the process break the T off line going to certain properties closest to where they where digging. As soon as the break happens on my property I was responsible for the repair cost to dig up the line going to the house and patch it. Happened to both my properties. Cost me $1700 per property to repair the lines at that time 20 yrs ago.
 
Have not replaced any faucets. Service line to street is ruled out by isolating that section by cutoff in the crawlspace and then observing meter. We have tested this at least 5 times. Yes, we get temps here in the 10-20 degree range. We double checked the washer drain line yesterday, will detach the dishwasher drain today and check calibration of the meter by measuring gallon usage while observing meter. We did the same with the last meter in place and found that with a strong flow, the meter was very accurate. When we dripped slowly the meter under reported at .6 gallons. Toilet flush showed .2 gallons more than we measured. We are showing 41 gallons leaked yesterday.
 
......... Do you know if there's a check valve in the new meter that they installed?

Water could be flowing backward through your meter and it won't be showing a reading of such. (They only read in one direction). Then it flows BACK through the meter as you consume it..... meaning your meter is reading your water usage twice, showing an excess. (That could be intentional..... and illegal). A check valve in your water line would stop water from flowing backward through the meter.

(Just grasping at straws, here....... but it is plausible).
 
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Can you post a schematic of your plumbing? Seeing where each line runs might help.
 
NorthernRedneck said:
I was just thinking the meter itself may be faulty.
Click to expand...
I think that he said the meter had been replaced three times.
Could it be anything as simple as air in the line that has migrated into the hot water tank. Do your taps splutter when you turn them on? Does the water coming out of the tap have air bubbles in it when you let it sit in a glass?
 
I do not have a schematic of the plumbing.3 new meters and they do not have check valves and do show occasional negative flow. Taps do not sputter and no aeration in water.
I do think that the meters are part of the issue as the leak only surfaced when a new meter was installed. Also this 3rd meter is showing more daily usage than the 2nd meter. We track our usage daily now as we are obsessed with this problem.
We confirmed again yesterday that no water was going down washer or dishwasher drain.
So hot water connections after hot water heater: Washer(same wall), kitchen sink, dishwasher, bathroom sink, upstairs branch feeding sink and then shower/tub, master bathroom sink, tub, shower, sink.
35 year old home. Decking and joists are visible in crawlspace and no wet spots showing. Base sills sit on cinder block, no wet blocks or sills. Water pressure steady at 72 psi from a county utility service. Neighbors do not report similar issues with new meters. Google searches on the meters do not indicate accuracy issues.
How could a leak change flow rate up and down with consistent water pressure? Changes from .17 to more than 5 gallons per hour seems unusual especially when the increase is always during our awake time and highest 8-5ish. To me that points to the meter.
 
tab58 said:
..... they do not have check valves and do show occasional negative flow.
Click to expand...
I recommend you install a check valve after the meter. (Or since it is in your hot water line, install one before the hot water heater?)

..... Hold on..... if hot water is running backward through your lines, the water inlet line will likely be warm/hot. Check that. It ought to be cold. If it's cold, dismiss what I said about the check valve before the hot water heater.
 
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Since you have checked every reasonable source of a possible leak, & the spikes began coincidentally with the installation of a new meter, I would focus on that. You have found no expelled water from a leak. You have done your due diligence.
It could very well be a glitch in the programing or circuit board sending false data.
Better said,,,,; call the utility.
 
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