Is this Storm Water Pipe ok?

[PatDIY_Dad]

Hey all. I have installed another storm water grate and I want to know from people here if its should be fine. I think it will. I cant foresee any problems

First a some background of the scenario and the use case

This area around this storm water drain is under cover of a attached to the home pergola. And in the coming weeks are are getting it screeded + tiled + covered with windows and sliding doors so soon it will be fully enclosed

The existing concrete has fall so the tiler suggested to install another drain if we ever do clean the area with a (hose I guess) but I think we will only really be mopping.

I knew there was a underground storm water pipe from the existing storm water drain you see in the background but before I cut the square hole I expected the connecting stormwater pipe to be straight but you can see its on an angle slighlty.

So I got a 100mm Snap on Tee and drilled a 50mm hole. I was able to get a 100mm to 90mm reducer and got a 90mm angle pipe connection. This allows me to connect a strom water grate a bit higher and level.

So now all the tiler has to do is cut the desired height and glue it

Now when we do rarely hose or pressure wash the area some water may pool where I have indicated in blue. I just wanted to check if that is fine if water sits there untill it dries out? Ill put some silicone in there so no leaks happen. Wouldnt it be just like an S trap pipe with water sitting there?

I honestly it will be fully inclosed so I dont see us using water hoses much apart from mopping the tiled floor 

( probably didnt even need to do all this work for a grate but anyway may as well now )