We have a new septic tank made of solid stone masonry. The masonry is held together by cement mortar and has been plastered with cement plaster.
A professional working on the job has ensured us that the tank is waterproof (i.e. it should not egress water into the soil.) However, posts online are telling me that neither masonry, mortar or plaster are waterproof.
So is this guy totally wrong? Do we need to apply a waterproofing system to the septic tank?