UPDATE BELOW!

Or How to Avoid Paying Beaucoup Amounts of Money for Septic Tank Locator Services. My advice:
1. Get the darned thing cleaned out every five to seven years!!!
2. Get the darned thing cleaned out every five to seven years!!!
3. Ditto!!!
Don't do what we did: live here for over 25 years not knowing exactly where the tank was situated or how deep it was, and decide to trust to blind luck until there was a problem.
We called a Septic Tank Cleaning Service today and the man came out and probed around the ground in the general area we thought the tank was located. He decided that the tank was sitting under our deck, about 2-3 feet in. So he recommended that we call a man who had a way to locate the tank using a long probe with a camera on the end. I called it a colonoscopy for the septic line, which made him laugh. He found that the tank was not under the deck (thank Heaven for that!) but about 2 feet out from it. He and his helper commenced to dig, and dig, and dig and 1 hour+ later, they had found the tank and the trap door lid.
Did I mention that this all started after dinner? It got dark just before they started digging, so after hours rates apply, of course......and it's Saturday, so those rates apply and geeze Louise, it sure costs a gosh-awful fist full of moolah!
The next step was to call the Septic Tank Pumper man again - which I did - but since it is Saturday night he is (wisely) not answering his phone or his pager. Perhaps he had a big night on the town planned and pumping yet another septic tank doesn't figure into it. I can't imagine why - can you?
I will call him again tomorrow morning; I sure hope he works on Sunday. If not, we might have to go to a hotel. As it is now, we have to be very careful flushing toilets, I can't wash dishes or clothes or take a shower. I sure hope that doesn't last too long......LOL
UPDATE: as of 10:30, the septic pumper guy is almost finished pumping a minimum of 26 years accumulation (ICK) and now we can shower, run the dishwasher, etc. Oh and I spent almost 2 hours cleaning the guest bathroom (double ICK) and it looks as though nothing icky ever happened there. YAY!!