Complex sentence: Neither exists there a public sewer system; deep holes are cut untill the groundwater in the coral as a pit for the latrine is reached, which pits are washed out twice a day through the coralrock by the high tide of the sea.
Split into simpler sentences: Neither exists there a public sewer system; deep holes are hacked in the coral rock untill the groundwater is reached for building a pit latrine. Those pits are washed out twice a day across through the coralrock by the high tide of the sea.