I have been learning a lot about drains and plumbing lately.
We have a drain in the basement floor of our new house, which we didn't have in the old one. It's right in front of the washer and we learned the hard way that the washer drains into this one. It started backing up when the washer would go into the rinse and spin cycles. Not a tremendous amount of water, but enough to be a bother. Google to the rescue on learning about these systems. Did you know that these drains lead right to your septic tank usually? And the small amount of water that is in these drains serve as a block to keep the icky smells from the septic tank from coming into your home? We're not sure what was blocking the drain, Hunny bought a 50 foot drain snake and got it unblocked. But, in the process of all my reading about these systems, I did learn a couple things. One is that on your drain hose coming from your washer, you should have a filter to keep the lint from going down the drain. I'm sure there is something you can buy, but what is recommended is taking old pantyhose and rubber banding it around the end of the hose. Then once a week, check it and clean it out. Simple as that. That will save you a lot of headache in the long run. Also, once a month, taking a cup of baking soda and a cup of vinegar and pouring them down your drains will help keep them clean and sweet smelling. To keep your septic system happy, you can buy Rid-x and flush that every month, or the cheaper route is to flush 1/2 cup yeast the first month and then every 4 months flush 1/4 cup yeast. I even read a packet a month. This helps keep the good bacteria in your system and actively breaks down the waste solids, even though with all that gets flushed, there should be a good amount of bacteria in there. This will keep the whole system happy and your drains running smoothly!