One of my tenants water bill doubled last billing period. How do I find where the leak is? How can I detect whether the leak is before the meter or after?

The leak would have to be after the meter to rack up excess usage. Look in the house somewhere for the leak.

The leak will definitely be after the meter. First check all toilets. If no toilets are running and you see no obvious signs of leak, turn off water at the main shut off valve at the house. Read meter, wait a couple hours and read meter again. If meter shows usage you have underground leak.

If you have a water conditioner make sure that it is in working order, sometimes the clock on them will go bad and keep them in a backwash mode.
To tell if you have a leak try this, make sure that all of your faucets are off, make sure that all commodes are not running. Then take an object such as a long screwdriver, place it against the kitchen sink faucet, listen for a noise that sounds like water moving in the pipe. If you hear it that means you have a leak. This will not help you find it but it will confirm that you do or don't have a leak.

If you have a water cutoff valve on the water heater you can turn that valve off and then listen again for the noise. If you had a noise the first time and then you don't have on the second try that means the leak is in your hot water line. If you determine that it is in the hot water line then you need to start feeling around on your floors for a warm spot, if you find one the leak should be close to that point.

Do simple test: Make sure nobody is using water in their house. Than, go to the water meter and see if it is turning. If positive, than go inside and investigate. Also, check sprinkler system, if any.

Additionally - and from my personal experience - if we have our in-laws to come over for their annual visit, our water bill doubles as well. It doesn't necessarily have to be leak but extra people living with you.

Maybe your tenant has somebody else living with them?

All good suggestions above!!

But first place to check is the toilet... Here, I place some food coloring in the tenant's toilet tank... then go away for an hour or so... when I come back if dye showed up in the toilet BOWL then I know the flapper is defective and needs to be replaced.

Sometimes the drip is so little that it will not show up at the meter as you watch the needle, but still will show up over 24 hour period and cost you money!

Start there... and also check with your tenant as MILO suggested... bills can double if he/she has friends dropping by more frequently than before... ;)

Let us know what you find!

MARK

First shut everything off in the house and check the little pointer in the meter face. If it creeps you have a leak. Herald had the right idea. Check the water service line first by closing the house shut off valve and checking for any creep in the little pointer. If the meter holds steady then follow the advice given above. If the toilets and other fixtures have no leakage then you have a hidden leak. If the house is on a slab then outside help such as Sleuth can be called in to pin point the source of the leak, jackhammer up the floor, bag the dirt and bare the leak. Good luck and let us know. Tom