50% increase of water consumption

[charles2]

I have an elderly couple who last month suddenly saw a 50% increase in their home water usage, according to the city water authority. It was about a 3000 gallon increase. The increased usage level has maintained this month. Yet they deny using substantially more water than they were in the summer, and I believe them. No leaks are evident anywhere in the house, and there is no sound of water running. I have not yet been in the crawlspace.

What could possibly cause such a sudden jump? Is there any chance that the meter (or the reader) is lying?

[jimbo]

The meter is not lying. Very unlikely. Turn off the main valve at the house. See if the needle is still moving. You may have an underground leak somewhere.

3000 gallons in a month is about 100 gallons per day, about 4 gallons per hour. An underground leak, or a toilet fill valve running full blast, can easily acount for this. Check the overflow discharge pipe off the water heater. If it is pipes somewhere, see if the pipe is hot, and find the end to see if it is running.

[charles2]

I don't think there is a main valve at the house. The only place to shut off is at the meter.

[Plumber Jim]

Also check the flappers on the toilets. put some food coloring in the tanks of the toilets and wait 15-20 minutes and see if the color makes its way to the bowl.

[Terry]

Or it could be that the meter had been "under read" before, and now they are current.

[Runs with bison]

Since this is two months in a row, reading errors are not likely the culprit. The first thing I would check is to see is if the meter was turning with no water running anywhere in the house. If it is turning then you can start turning shut off valves on individual things to see if any halt the needle.

If the needle is not turning then some major water user in the home is not working right. Perhaps a toilet flapper is hanging too long and they flush a lot? Flappers like that can be tricky if they are hard of hearing. It might only get stuck occasionally but could waste a prodigious amount of water until the next flush unsticks it. Check to make sure the water levels of the overflow tubes are not very close to the top as well. If they are the valve might occasionally be trickling over for hours on end.

I assume they have no irrigation?

The meter could be wrong, but it seems unlikely. You could measure out some known quantity (e.g. 5-10 gallons) as a check of the meter. This will prove the meter right or wrong. All you need is some sort of calibrated receptacle. If it appears obviously wrong after such a check, then have the city check and replace it. I assume they would get some sort of credit for the months that are out of whack.

For perspective on the size of this discrepancy: my family of 4 is using a little over 3,000 gallons/month at present with roughly 40% of that coming from the 1.28 gpf toilets. That total is likely half the use of an average family this size, but in addition to the HET's we have low flow showerheads, a front loading washer, and an energy star dishwasher. (On the other hand, we don't eat out much and like to cook, which increases our water use for clean up.)

p.s. You did check that the days covered by the meter reading cycle are similar, correct? Sometimes we have a 25 day period followed by 37 days...with a predictable impact on monthly usages both in the short and long cycles. Convert this to a daily use for comparison.

[Cass]

I have seen where toilet handles will stick in the down position for hours then release allowing the flapper to fall...most of the time it has been on old AS toilets...

[hj]

Water meters can register low if the disc starts to get sluggish, but they cannot "speed up" to overregister usage. It is probably a leak outdoors, an underfloor leak if it is a slab floor, or a toilet leaking.

[charles2]

Hey thanks for all the tips, everyone. I went back over to the house and strained to hear a toilet running, shut off its angle stop, went out to the Neptune meter and it stopped turning. I had no idea such a quiet leak could add up to 3000 gallons per month!

[Plumber Jim]

Good to hear it. Yea, people find it hard to believe that a toilet can waste soo much water but they can.

[Inspektor Ludwig]

Here's a question, did they recently replace their hot water tank? Most hot water tank companies will automatically install an expansion tank even if the house doesn't need one. The problem is that some meters will read water usage going to the house AND any water that may be going back through the meter due to the expansion tank. While normal expansion does occur in a house without a tank, it's so slight that it's never noticed by the meter but the expansion tank causes the water to flow in and out all day long. It can add up to a HUGE water bill. We've seen it where I work and we've traced it back to expansion tanks installed on open systems.

[charles2]

Here's a question, did they recently replace their hot water tank?

No, no plumbing changes whatsoever.

[Runs with bison]

Hey thanks for all the tips, everyone. I went back over to the house and strained to hear a toilet running, shut off its angle stop, went out to the Neptune meter and it stopped turning. I had no idea such a quiet leak could add up to 3000 gallons per month!

Cool! At least it wasn't hot water...it bites twice as hard.