On Thu, 18 Jul 2019 22:14:01 +0000, Hendu
m wrote:

I recently bought a home with a septic tank. I have never had one before so I
am trying to learn all I can. A couple of weeks ago we had a very bad rain
storm and sewage from my septic tank backed up through my basement drain. It
was very expensive to clean so I plan to take measures to prevent it from
happening again. From discussions with a couple professionals, I believe the
cause was a stream of water running downhill through my yard over my tank
covers. Enough water entered to fill the tanks and forced water/sewage up
through my basement drain which sits lower than the tank lids. My thinking is
that with some waterproof caulk (or Flex Seal (TM) ) I could make the concrete
covers waterproof in case of another severe storm. I know this is where the
tanks are accessed for cleaning, but the seal could be broken with a utility
knife for this maintenance. Is there another risk I am not aware of to making
these covers waterproof (and probably air tight)? Thanks for any
advice/suggestions

My pumper guy uses spray foam to seal the covers when they pump them.
It should breathe out through the drain field. If that is not working
right, suspect a bad drain field. It may just be a bad pipe to the D
box if you are lucky (between the tank and the leads out into the
field)