Hole in the bottom of the air box

What is the purpose of the dump valve at the bottom of the air box on a TD5 apart from potentially letting water in ! The rubber cover keeps falling off and the last time the car was serviced by a garage (several years ago as I have given up with any of them doing a reasonably job) it came back still full of mud. I am thinking of blanking it off or running a tube from it up to the other breaters in the engine.

in a tractor or machinery in dusty conditions with cyclone filter it lets dust etc out ,but on a square box any water that enters

That would be deep water to get in the bottom of the air box and your feet would be getting wet long before that. Its there to let any water out that may be sucked in the intake such as rain etc. Similar to the one on the heater air intake.

Don't want ANY water in the air box regardless of where it comes from. Looking at a Defender thread they seal up any drain holes. There is also another small square hole in the bottom of the box which I have filled with sealant.
Seems pointless having the main intake at the top of the wheel arch, reasonably well protected when the box resembles a sieve !
I'm going to start another thread asking why anybody fits a snorkel to a Discovery TD5 when the air box is full of holes !
BTW it's been a bit damp in Suffolk recently and I've seen 2 Discoverys abandoned in water which hasn't been that challenging, and I've kept my feet dry.

When fitting my snorkel I found plenty of holes leading up to the air box, and dilligently sealed them up - as instructed - including the air box dump valve... was this a mistake???

If water does get in how can I get it out (assume an over zealous use of the hosepipe by bob-a-jobber washing the car!)?

If it's sealed the only way water can get in is if ya shove the hose pipe in the snorkel top. Stick a bucket or bag over the snorkel top, before letting him loose with an hose pipe.

I think I might fit one of those pre-filters off a tractor in place of the air ram...

just blank it off, i have blanked of our entire fleet and have more peace of mind as no water can get in from there now, also blanked the pre fitting on the hose before it reaches the air box, all closed up, only one way in, thats through the snorkel, and if you go through water that deep, yo probably deserve to have water in your air box.