I received my second quarterly water bill and cannot believe it says I'm using 49,000 gallons of water each quarter. That's over 500 gals per day!

So I started thinking about average water usage per appliance, shower etc and it still does not add up. The only thing I can think of, is maybe the water passed through the radiators is the culprit? I've tried searching online for an answer, but no dice.

While I do know my home heating is based on hot water passing through radiators and baseboards, does this mean its an open system? Therefore, whenever the water passes by all the radiators then it leaves the house and into the sewer? Hope not, since this looks to be inefficient to me. I would assume home heating systems that use water are closed systems and not lose water.

Maybe I'm barking up the wrong tree on what's consuming all that water, but at the moment, I need to understand how water circulation works in radiators.

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    Do you have an irrigation system? If so, it there a really soggy spot in the yard? Are you filling all your neighbors pools, or a killer whale tank? You don't have a fixture hooked up like this, do you? I'd contact the water company to come take a look at the meter. – Tester101 Jan 7 '13 at 14:43
  • In addition to a leak, it's possible for the water company to mis-read the meter. – BMitch Jan 7 '13 at 15:15
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    Round here, the water company estimates my water usage for long periods of time, and bills me accordingly. Every once in a while someone actually reads the meter, and whatever discrepancy there is between their estimates and reality crops up as unusually high or lw usage in a single bill cycle. – Wayfaring Stranger Jan 7 '13 at 16:12
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    Before you go to bed one night, note the reading of your water meter. When you wake up, check it again. If it's different by more than a couple liters (to account for say refilling your heating system) then you likely have a leak somewhere. – Steven Jan 7 '13 at 17:31
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    Simple step (but doesn't answer your question): look at your water meter. Is there water flowing? If so, likely something is leaking. Start turning off valves to appliances (shut-offs under sinks, toilets, outside taps, at your furnace, etc) until it stops. If not, you may just have to keep track of the readings throughout the day as much as possible, and see if you can isolate usage to something or some time in particular. – gregmac Jan 8 '13 at 5:25

To answer your question, the radiators in your home are a closed loop. If they are single-pipe steam radiators, then there is a small amount of vapor loss out of the little valve on the radiator. (The one that may hiss a bit while warming up.) If you have that type of system, the water level in your boiler must occasionally be topped up, but that would be a few gallons of water per month. But if your heating system was installed in the last few decades, it's more likely you have the much more common forced hot water, which is an entirely closed loop.

My guess is that your meter was misread, or the meter is faulty.


There are several possibilities here. As others have said, hot water heating systems are closed loop. The water is returned to the boiler, with little loss. Even with steam radiators, the steam condenses and most of it drains back.

There are other places the water can go. You might have a bad toilet valve. Surprisingly, a leaking toilet can be a huge water user, constantly running.

Even a badly dripping faucet can be a cause. Maybe a hose bib that you don't see normally. Or you might have a leak in the plumbing, hidden in a wall.

Are other members of the house using more water than you think? 500 gallons a day is not impossible.

Finally, there may have been a mis-read. You can always check the meter yourself to see if that happened.


No, it's not an open system. Whatever your consumption problem is, it's not your hot water radiators.

Sounds to me like the supply line between your meter and your house may be broken. But that's just a guess.


Unless you notice water leaking somewhat noticeably from either radiators or around boiler/piping it is not the heating system. Closed loop works like.. amount that leakes out gets automatically topped up by autofilling valve. Lose a gallon it will add a gallon... though the valve is actually activated by the drop in pressure caused by loss of water in heating system (lose 5 psi, it will add water until 5 psi is added)

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    This adds nothing to the existing answers. – Chenmunka Feb 5 at 9:03

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