Homeowner's monthly water use jumps to 34,400 gallons before discovering issue with unused toilet

A homeowner got a costly reminder that even a seemingly minor plumbing issue can send water usage soaring.

The homeowner turned to Reddit after noticing their monthly water consumption had jumped from about 2,700 gallons to 34,400 gallons. After investigating, they traced the spike to a toilet in a rarely used bathroom, where a malfunctioning fill valve appeared to be continuously spraying water into the tank.

What happened?

Writing on Reddit's r/Plumbing, the homeowner said: "I just looked at my new water bill this morning and it's a lot higher than last month. It was 2,700 gallons, now it's 34,400."

The toilet discovery occurred during a hurried check of the house before work, when they traced the spike to a bathroom that was not regularly used.

"Discovered a half bath attached to an unused bedroom has a fill valve that is audibly spraying water from the top," they wrote.

Plumbers in the thread urged the homeowner to shut off the toilet's water supply immediately.

Luckily for this homeowner, many also said replacing the fill valve is often a simple do-it-yourself job that takes about 20 minutes.

Why does it matter?

Problems like this can stay hidden for a long time when they happen in bathrooms no one visits often. In that situation, a toilet leak can dramatically increase your water usage before the next bill arrives.

Commenters pointed out that while a 32,000-gallon jump sounds almost impossible at first glance, a leak of the size described by the original poster could realistically account for that level of water loss.

"30,000 gallons a month is 1000 gallons a day is 0.7 gallons per minute. This is a totally credible number from that kind of fixture," one commenter wrote. 

"At full pressure you could see up to 100,000 gallons in a month from a neglected fill valve/flappers alone," another added. 

What can I do?

If your water bill suddenly spikes, one of the first places to check is the bathroom — particularly any toilet that does not get used often. Listening for hissing, running water, or spraying sounds inside the tank can help identify a hidden leak.

Commenters said to shut off the water supply to the affected toilet immediately. Doing so can keep the bill from climbing even higher while you figure out the next step.

From there, commenters said a full fill-valve replacement is inexpensive and manageable for many homeowners to tackle themselves.

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