Oh the days of the septic tank in the garden, it definitely used to help keeping water coming up for the plants, however let's get back to the cleaning part....

Outlet points from the home, an easy way to collect excessive fats and oils, a trick I learned many years earlier was your wife's old pantyhose (in our home mine). Cut the legs off, roll up around pipe tying onto the pipe, lay the foot section neatly on the grid entering main pipes leading to sewer. Using this method (especially from the kitchen) captures excess which you untie and throw away every second week.

Plumber rods for main pipes leading down from home to garden where your opening you revealed helps clear pipes through to that section, then yes that high pressure hose treatment for the rest.

Over the last 20 years we have been on main line system, the septic system was missed during the drought keeping the garden moist throughout the year. Having old systems need more attention,

I still use the old system ideas to keep excess fat from kitchen going down to the local water plant, pantyhose trick for kitchen buying cheap pairs exclusively for this. Think a little ahead of what we putting back into the water you end up drinking eventually.

Catching up with tedious tasks keeps us on our toes, have a great day 🙃