flooding damage, who pays

I can't understand the link between the drain cover screw and the water flooding? In order for a leak to happen pipes must surely have been split or knocked out of position.Did you poke anything down the plug hole to try to get the screw back,like a wire coathanger?

I can't understand the link between the drain cover screw and the water flooding? In order for a leak to happen pipes must surely have been split or knocked out of position.Did you poke anything down the plug hole to try to get the screw back,like a wire coathanger?

The pipe that comes into the tub from below does not connect flush with the bathtub and there was a large gap between. The only thing holding it together and making it watertight (ish) was the screw that goes down the middle of the drain into a connector in the pipe below. Without the screw the hole in the tub and the pipe below match up but there is the gap where it seems the water leaked.  So no I didn't move any pipes or break any pipes

Surely if one knew the important role of the screw,you would not continue to let water pour down,and would insist on urgent repairs? I am assuming you only found out afterwards. If not,then I think your landlord could hold you responsible for paying at least the excess. 

One doesn't usually have to mess about with mechanical fixings to eradicate a blockage. It's starting to sound like you did this to yourself... did you try any unblocker products first before you resorted to unscrewing things? What appears to have happened is that you undertook some (what I'd call) DIY and it went wrong - the loss of the screw - and then you just left it... I mean, that's harsh, because you told someone, but it's unlikely they truly understood what was going on (although someone would ideally inspect)... you continued as if nothing had happened... but you knew it had. You obviously knew that screw was there for a reason... mostly they [screws] are. Whether flooding is willful or accidental shouldn't really matter... because it was your actions that instigated it... unless you can prove otherwise, of course.

thanks I understand your points and see what you are getting at -  ie: I did something to cause the issue so my fault. I would say however from a legal standpoint I think the landlord would have to prove that I am negligent. If I kept the dropped screw a secret and denied orders then sure this is possible but I never did this and informed them of the screw incident, I'm not a property lawyer expert person but from reading on the subject negligence is complicated subject, eg: if a tenant runs a bath and overflows the bathroom causing damage you would think the tenant is responsible (the tenant did 'something' to cause issue so their fault right?) but it's usually the landlord who is responsible as the bathroom should have overflow protection in place, or maybe they did have overflow protection and the tenant then is responsible for covering it etc.  so yes I did 'something' but was this negligent or not is not easy to work out, I guess we could ask 20 people and get 20 different answers.

Oh well... at least you didn't come here with a fixed outcome in mind.

not at all, just was wondering if anyone had similar experiences and what the outcome was.

The screw is an important piece in all baths/sinks that i have seen. I would fully expect it to not sit flush if it is removed.

Seems like an accident, the root cause being the removal of the screw. How it is paid for will have to be discussed between you and the ladnlord. They might not want to claim on insurance because their premiums will increase for a number of years. I would personally be asking the tenant to pay for the flooding repairs in full.