I don't know the answer, but I learned my lesson on letting septic tanks go for years unpumped (11, in my case). I , uh, spent a few weekends improving my drainfield.

There's nothing more remindful of one's own mortality than standing shoulder deep in a huge hole created by my own efforts at my somewhat advanced age..

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80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)