Water loss in the house is estimated by some to be as high as 12% which is astounding when you think about it. If you use 80 gallons of water per day which is the average per person usage in the U.S. this means you’re literally flushing almost 10 gallons of water down the drain each day through waste.
I did some research and found some wildly contradictory results when I asked how much water does a leaking toilet lose. I read anywhere from 20 gallons per day to 200 (!) gallons per day. So I decided to do more research to get the correct answer and here’s what I found.
Water loss from a toilet leak may be constant or intermittent and is determined by the water pressure into the toilet tank along with leak size. A badly leaking toilet can lose 3-5 gallons of water per minute so losing 20 gallons to 200 gallons per day is not out of the question.
Water loss from a leaking toilet
After much research, it dawned on me that there are reasons why people suggest that a leaking toilet may waste 20 – 200 gallons of water per day. It’s a wide range but then again a leaking toilet has many different possible factors:
What is the water pressure to the toilet? Some people open their toilet water shut off valve all the way to allow the maximum flow in. Some people close the toilet water shut off valve slightly (I do) to minimize the flow to just enough to fill the toilet properly. Opening the valve all the way is overkill in my opinion as it can only fill so quickly and the more open the valve is, the bigger the flood you’ll have if the hose bursts or starts leaking.
How big is the leak? Of course this matters too. Is the leak coming from a toilet flapper that is slightly ajar or damaged? Or is it an improperly operating flush valve assembly, rusted pipes, toilet bowl condensation, worn out wax toilet seal, a crack in the toilet bowl or something else?
Does the leak come and go? If the leak comes from the rubber or plastic toilet flapper, the flapper can sometimes reset itself and stop leaking. And then start up again. Toilets can also waste water when the float is set too high and the bowl is overfilled. Water then leaks into the overflow tube. It may also come and go. Perhaps your “leak” only occurs when it rains heavily. More on that below.
Bottom line: Leaking toilets can have different rates at which they leak and thus cost you varying amounts of money.
How much can a toilet leak per day?
The EPA suggests that around 30%
of home water usage is from toilets. This is the single greatest use of water in the home. It stands to reason then that the leaks from toilets – especially if you have more than one in your home – can also waste the most.
It’s also known that water can escape from an open toilet fill valve at a rate between 3 – 5 gallons per minute. That’s 180 – 300 gallons per hour or 3,780 – 7,200 gallons per day of wasted water. Even at the lower end of around 4,000 gallons per day, that could cost around $50/day depending on your local water charges.
Even cut that in half and you’re still wasting $25/day.
Now a constant water leak is probably something the average person would at least try to look at, as the constant running sound of water is usually noticeable. The sound alone may cause you to at least take a look and wiggle a few things in the tank to try to get it to stop.
But if you have a constant leak and refilling of your toilet tank when it’s not in use or when you’re not even home, you are wasting a significant amount of water and money.
How much water does a leaking toilet use and cost?
The bigger the leak, the bigger the waste and the more money you’re spending. The table below shows expected wasted water in gallons and money spent in dollars per year on water leaks in general inside the home.
NOTE: This table could apply to any water-using device in your house but as you can imagine, your toilet can cause a much bigger and costly leak than say a faucet.
| Drips per minute | Wasted water per month | Wasted water per year | Average Annual Cost for Water And Sewer |
| 10 | 43 gallons | 526 gallons | $10.91 |
| 30 | 130 gallons | 1,577 gallons | $18.44 |
| 60 | 259 gallons | 3,153 gallons | $36.81 |
| 120 | 518 gallons | 6,307 gallons | $73.59 |
| 300 | 1,296 gallons | 15,768 gallons | $184.12 |
How much can a leaking toilet increase a water bill?
If you consult the table above, you can see estimated water costs for leaks that you might experience in your home. The total money wasted of course is a combination of the amount of wasted water multiplied by your local water cost. Water charges can vary wildly depending on where you live.
Here are the 10 most expensive states for water costs assuming an average family and usage. If we assume the 12% water loss figure quoted above, you can take 12% of each figure below to estimate your monthly water loss. And that’s on average.
As the table above shows, a toilet can lose far more water than “average” when leaking at upwards of 3 – 5 gallons per minute.
| State | Monthly Water Cost |
| Alaska | $95 |
| West Virginia | $72 |
| Connecticut | $69 |
| California | $65 |
| New Jersey | $64 |
| Utah | $58 |
| Hawaii | $57 |
| Washington | $57 |
| Wyoming | $52 |
| Kentucky | $49 |
The costs of toilet water leakage add up over time. While they may not dent your wallet as much as you might think, often the cost to fix them is much smaller.
How to detect a leak in your toilet
Maybe you’ve noticed a sudden uptick in your water bill with no noticeable increase in water usage that you’re aware of.
You might hear a water leak in your toilet from the sound of the running water. Other leaks are relatively silent and you might only hear the toilet suddenly refilling as the float inside the tank lowers to a point that triggers the refilling.
Of course, if the leak ends up on the floor of your bathroom, it’s a bit more obvious. If the leak is underneath the toilet due to the positioning of the toilet on the floor, the leak may not be visible or heard.
If you’re unsure if you have a leak or not try this: Take the toilet tank lid off, flush the toilet once and when the tank has emptied, put a few drops of food coloring in the tank as it’s refilling. Wait a few minutes and check the toilet bowl. If there is colored water inside the toilet bowl, you have a leak. The quicker you see the food coloring the bigger the leak.
Why does my toilet leak when it rains?
Can heavy rain affect plumbing inside your house? Yes, it can. So it might not be your toilet leaking per se but rather storm water overpowering your sewage system and backing up into your home.
If you find that your toilet doesn’t flush or empty properly during or after heavy rain storms, it’s typically one of several reasons and in both main cases it’s likely there is a blockage somewhere:
- It’s possible you have a blockage in the sewage pipes leading out of your home. In this case, the extra water entering your city’s sewage system from the rain draining ends up slowing down and backing up your toilet which can’t drain fast enough.
- The pipes are leaking and you have a blockage. It’s possible that the sewage pipes underneath and near your home are cracked, leaking or otherwise impaired. In normal circumstances when there is no rain, your toilet may be able to empty properly and water is able to escape through the pipes including through the damaged area. But with heavy rain, the ground and earth is already saturated with water and can’t absorb any more. So in this case, you have slower drainage of toilets from your home.
How much water does a running toilet use in a day?
I already wrote a detailed article on this website called Cost For Toilet Replacement Is $0 where I discussed how I spent around $25 each (including rebates) to change three toilets in my home to water-efficient low flow dual flush toilets. The resulting water savings on my next water bill alone paid for the cost of the toilets and then some.
A low flow toilet uses much less water per flush than older style toilets. A dual flush toilet has a full flush option for solid waste and half flush option for liquid waste.
In a nutshell, modern toilets may only use 1.1 – 1.6 gallons per flush each time but older style ones in the 4 GPF – 7 GPF still exist. The more water your current toilets use the more you can save when you switch to a modern water-saving toilet, just like I did.
So while you can save money by fixing leaks, you can probably save more money by switching to low flow dual flush toilets throughout your home.
Summary
What should you do when you experience any of the above-mentioned problems with your leaking toilet(s)? While some fixes might be ones you can do yourself if you’re handy and motivated, others might require help from a plumber. Certainly the last example when your toilet seems to leak or not drain properly when it rains is something you need professional help with.
In my experience, some leaking toilet issues particularly from inside the toilet tank may be ones you can handle yourself. I consider myself somewhat handy but self-trained and I’ve replaced three toilets completely. I also replaced the insides of the old toilet and replaced the flushing and valve mechanism in each. I’ve also replaced the toilet water supply hoses leading into the toilet and once took one toilet out and fixed a blockage caused by my younger daughter’s toy being flushed and getting stuck.
But you do need to be careful because you don’t want to get into a situation where you “fix” something with your toilet, experience a bigger leak or flood that causes water damage and find out that your insurance company won’t pay for the damage since you caused it.
And if you consider putting something in your toilet to reduce the water usage in the tank, you might want to read my article Should I Put A Brick In My Toilet Tank? (To Save Water) first.