wierd cement covered hole in back yard

[cateyanne]

Hi! hope somebody knows something about this thing! We recently purchased an older home and directly behind the back of the kitchen is a square hole. It is cement lined with a cement cover. It is full of water and smells, sometimes a little sometimes not at all. The water is sometimes lower than at other times. The opening is about 24 inches by 18 and the depth of the hole is about 3 ft. The home was built in 1941. Is this some old fashioned devise, or what. Anybody got a clue ? We'll take any ideas, just send 'em my way. Thanks!

[HayZee518]

It could be a cistern, used for drinking water -or- you just found the cleanout hatch for a septic tank!!!