Note to self when building an underground cistern: create a sump pit at one end. PS- That looks like JB Weld. PSS- It's very satisfying to hear the water pouring into the tank.
gonna need to do this too, thanks for the vid! i wonder what i'll find at the bottom, since the house was built in the 1890's... the access was removed by tiling over it by a previous owner around the 60's
Re ventilation, I have found that an extract fan with flexible duct works well , just place end of duct where your working or at end farthest away from entrance.
