It will be underground somewhere outside of the house.

And yes heavy trucks can damage septic systems.

Go into your basement and see where the main drain line, usually 4 inch diameter) exits through the wall. That narrows it down to where its located in the yard.

Thank you for your answers. However, where do I look for the drain pipe, since I don't have a basement?

you cannot rely upon where the house sewer exits either because they often make a turn and run a fair distance to the septic tank.

And yes a heavy dump truck will damage a septic tank, It will actually break right through the top and believe me, it is very expensive to get a truck lifted out of a septic tank.

Have you ever had your septic tank pumped? If it has not been pumped since you lived there you might be able to contact a previous owner to see if they can tell you, or if you live in a smaller community that only has one septic tank pumping service you might get lucky by calling them.

You might call or go to your local zoning office. In most communities they maintain a record of the actual location of septic tanks.

You can try probing the yard with a thin metal rod about 3/8" diameter. The make a probe just for this application that can be purchased at most hardware stores for about $10.

If all else fails I would suggest having the rock dumped on the drive way and move it by hand to where you need it. I know this is not the answer you want to hear, but take it from experience it can certainly be the cheapest solution to the problem.

They ought to make an expendable, flushable RF device that you could send down the john and then track down the tank with a receiver.

You would have to confirm with a probe, but it would get you in the right area.

The leachfield is also a problem relative to heavy trucks. So when you find out where your septic tank is, also find out where your leachfield is and don't let them drive on that, either.

The usual way is to go to the planning/building inspection office and see what's filed there. If that works, then verify that by using the "follow the drain line and push a rod into the ground" system (*smile*).

The poster that mentioned pumping is also right, in that pumping is part of normal maintenance...if you have been living there for a few years you should be thinking about that, anyways. Normally, a tank will be pumped during escrow, when a house changes hands as part of the general inspection process, so the company that did that might be able to help you...that company would have a report that should be among your escrow papers.

-Roger

also, you should ask how many tanks your house has. mine has 2, 1 for the bathrooms and 1 for the kitchen and laundry. the bathrooms tank is concrete, and were TOLD the other was as well, but last week when i dug it up to have it pumped i found out it was a steel tank that was probably original to teh house and looked as if it had never been pumped. this is rare though, th ebuilder of my house just happened to believe in doubling everything!

if you know where your outside cleanout is, you can start probing there and head away from the house. there should be a cleanout at every place that the line turns more than 45degrees, but not always so you will just have to keep probing until you find it.

the only way i knew where my tanks are was the bathroom tank had been pumped a few days before we closed and i had to fill the hole back in, and the one for the front had a partially caved in lid and thsu created a depresssion in teh ground there. plus when i was snaking the line i could tell approx how far it was by the length of my snake.

"You might call or go to your local zoning office. In most communities they maintain a record of the actual location of septic tanks."

In many locations septic (and wells) is approved by the local health department.
They always keep records.