I have had a septic for 20 years and I use Scotts regular. This is the brand that was recommended by a plumber and my septic guy. It is like using sandpaper on your skin but it doesn't clog the septic. You can see for yourself if you wet the Scotts it immediately falls apart. You can look at other brands and just put some water on them and see how fast they break up or just go with tried, true, rough and cheap Scotts. When my kids complain I just tell them that when they use a puplic restroom they will fell more at home because the paper is usually equally as rough as the Scotts.

If water can not pass through the septic tank to the leach field and dissipate then you have a problem. Either the tank is plugged at the outlet or the lines to the leach field are clogged or the leach field itself is saturated. Leach fields have a finite life and when depleted they can't simply be dug up and replaced. Recent code changes have mandated an outlet filter at the septic tank outlet. That filter can clog and stop the flow of water out of the septic tank. Whoever pumped the tank should have located that filter (if installed) and cleaned it as part of the pumping service. You should contact a licensed septic contractor and have them inspect and diagnose your system.

"Maybe I need a new, more curious, septic company." On that I believe we can agree. While it's true the tank(s) wouldn't ordinarly require pump out this soon,they should show more intrest in the problem by giving you answers you came here looking for. How long has the system been in service? Is the cloths washer on septic? Do you use bleach? Is the dish w detergent septic friendly? Just for grins do a neter check to eliminate unknown leak that could be filling tank. According to your observations at the clean-out,you can ignore all lines upstream from there until clean-out isn't standing water. Conventional septic systems don't lend themselves to diy troubleshooting and even if they did,less than 1% of homeowners are willing to get that down and dirty. With your above average determination,you may find the problem. It shouldn't be more than 20 feet from house to tank which is easy to snake. How certain are you of how many tanks you have? You can fihd out probing with a steel rod ,preffibly one desighned with tee handle for the purpous. How confident are you they were ALL pumped and inspected? Were you there or did you at least notice how many places were dug up? Do you know how and where the leach field is laid out? The difference in grass between functioning and nonfunctional laterals is not easyly detectable other than after long drought conditions,even then only if system is handling alot of water. When this happens without obivous reason,I normaly suspect a problem with first 6 feet of line where it leaves tank to leach field. The line normaly leaves tank about 2 feet below surface,runs 2 or 3 feet before turning down to 3 or 4 feet below surface and level with leach field or distribution box. It is within these crooks,turns and connectors that ground shift or settleing can have the worst effect by crushing or pulling apart. It's a rag tag method of determining if leach field is failing ( #1 reason for septic problems) but digging that first section up can help reveal a failing field. Additional to the obivous tools,have on hand , 10-32 or larger stainless steel screw,self tapping or with tap,drill motor and proper bit for tapping the screw. A sump pump is desirable just in case it's needed but if there is a rental or retail nearby the pump can be deffered until and if needed. While water is backed up as it was in your discription,drill hole at lowest point you have exposed. No water or only droplets with zero pressure definitivly shows problem is toward house. A stream squirting tells you the problem is downstream. Now use the screw to plug the hole. Tree roots are common. Leach field failures are a whole new kettle of fish so lets don't go there until absolutly nessary. Noone envys you. Good luck

Okay, toilet 101: Only fresh water enters the toilet tank (the part that sits on top in the back). When you flush the toilet, water flows from the tank into the bowl (the base, the part you sit on, where the waste matter goes) by gravity and from the bowl into the toilet drain line and down to your septic tank. There is NO WAY for anything from the bowl to flow to the tank. It is not physically possible, unless your toilet is installed upside down on the ceiling, but I'm certain you would have noticed that. The reason you have black stuff is that a toilet tank is mostly stagnant water, making it fairly easy for mold or bacteria to grow in it. Since you are on a septic system, you should not use bleach tablets, but you can turn off the toilet supply valve, flush the toilet until the tank is fairly empty and then scrub it. You can even spray it with a mild bleach solution (a one-time application will not harm your septic system). Then open the toilet supply valve and go back to using your gunk-free toilet.