Hello there: I recently bought a new house with a bath rough-in in the basement. I'm getting ready to finish the bathroom. The bathtub drainage is in a square hole (approx. 12 in. deep) that is full of water - seems to be ground water. I tried emptying it up, but keeps getting full. What is this? Does is stay there under the bathtub? Do I need to cover it or seal it? Will it cause water problems down the road? Thanks in advance for any advice!!
if it is a box where a shower or tub can be installed in the future it is a p trap for that. i usually don't glue these fittings so they can swivel and adjust to whatever is used. i am bad about just taping the top before i cover it with dirt. this will hold some water but time will create a leak. the plumber should have sealed this good if he knew it was for future use. sounds like sewer water to me. it might be water coming from another tub or possibly a sink. that may be why it looks clean and doesn't smell. use care anyway.