Bathtub bringing up water and dirt?

If your bathtub is in a lower location than the washing machine, you probably have a clogged main line. This should be augured out by a professional soon, or you will end up with a real mess on your hands.

The causes of the problem could be anything from roots growing in to the drain pipe to a child's toy or shoe partially blocking the drain. Eventually the drain will be completely blocked as it traps more and more waste and resulting in everything you flush or wash down any drain to back up into that tub.

Fortunately a professional company can use a power auger and clear the blockage relatively easily. You landlord should pay for this service by the way. You should notify them right away and get something in writing stating either that they will arrange for the plumber and pay them directly, or that you can and deduct the cost from the rent.

Does the toilet work correctly and does the bathtub drain properly? ie, do both drain quickly when flushed or emptied. You may have a partial blockage in the pipe that serves those 3 (or more) fixtures. You should try probably try running 30+ ft of snake down the toilet.

When stuff from other drains is coming up in the toilet its never good, usually a sign the main sewer line has "issues". I you are using a septic system, it might be time to call in the "honey dippers". Regardless of the cause, the landlord should be paying for it.

Slow drain or a venting problem.