For about the past year or so, we've occasionally noticed a small puddle of water on the floor of the unfinished side of our basement near where the pipes exit the basement walls and enter the septic system. The water doesn't smell of sewage.

There are two pipes that enter the wall at this location. One is the main pipe that everything seems to feed into to go to the septic system. The other pipe is open on top, about 20 inches tall. It has an "elbow" at the bottom where it enters the wall. The tube from the furnace condensate pump empties into this pipe. (What is this pipe called? Is it a standpipe?)

We think the water is coming from this opening, as there doesn't seem to be a leak in any of the other pipes. Occasionally when the washer drains, we will hear gurgling coming from this pipe, especially if I've done a lot of loads in a row. We do have a large capacity washer.

Yesterday I did about six loads of laundry. I heard a lot of gurgling, but the floor stayed dry. However, last night when I emptied the jacuzzi tub and flushed the toilet at the same time (it's possible the dishwasher was draining then, too) a large amount of water ended up on the floor.

A few pertinent facts: House is 13 years old. We're the only owners. Three people in our family. Septic was pumped 2 years ago. Only other plumbing thing I've noticed is that the other tub (not jacuzzi) seems to drain slowly. I noticed this when I used the shower in this tub. Water was up around my ankles. No backups of the toilet or sinks. Freestanding shower drains fine.

My question is this: Does it sound like a septic problem (overloading the drain field with water) or a plumbing problem (possible clog somewhere?)

Thanks for your input.