The pipe coming into the septic should discharge into the tank above the water level of the tank. If the tank is full of water so that the inlet pipe is flooded or, it is up to the top of the tank then you do have a septic problem.
The water is not making its way across the tank and out the outlet to the leaching fields fast enough for the volume of water you are using.
There may be a few things that can cause this to happen....
- Toilets with leaking flappers and dripping or, running faucets can put large amounts of water into the system. Sometimes fixing the leaks can make problems like this go away.
- Doing many loads of laundry on a single day should be avoided. Instead do a load everyday rather than have wash day.
- Sometimes there are weather conditions that cause high groundwater levels, When you know these conditions exist you should curtail water usage to avoid problems.
- When a tank is in need of cleaning sludge and scum meet slowing the flow of water through the tank this can cause the tank to fill.
- Some tanks have a filter on the outlet which can cause the outflow from the tank to slow when the filter is clogged and needs cleaning.
- Lastly is the gloom and doom one where your leaching field has problems and needs repair or, replacement. This is expensive! If this has happened I would recommend keeping the existing field in place and installing a second field. The old field will regenerate after a couple of seasons of non use and be ready for use again. With alternating fields you will probably never have a problem again.
I hope that your problems are minor and this advice helps.