The folks at Chicago 2-Flat tore up a concrete slab in their backyard to discover a 100-year old drywell located just next to the house. They considered setting up rain barrels as the only gutter drained into this drywell but decided against this due to the weather and limited space in their yard.
Instead they rebuilt the drywell by improving the drainage and re-sealing the pipes. In doing this they used oakum which made of loose hemp or jute fiber and sometimes treated with tar, creosote, or asphalt. It’s been used for hundred’s of years and is the perfect material to seal pipe joints.
As long as the drainage keeps the water away from their foundation, this drywell is good for another 100-years.