Bad eggy smell and water in front passenger seat

classiic HVAC failure? LHD left hand drive car , no country told.
own for how long, 2years or 1day/ or what ( right passenger door?) for rain. ingress.
you said water, well that can be clean pure water
from RAIN or HVAC evap condensate,
using AC cool or heat + defrost mode? or just pure heat mode?
I do not know what you do there
i tray to capture water,in jar,and see if it is green or yellow or pink
that is AF antifreeze,
and put my fingers in it and rub fingers to thumb and it feels very very slippery, that is AF. not water
if i sniff it and smells sweet it is AF>
(3 ways to discover AF antifreeze)
ok it's water, so dont use AC or Defrost mode.
so that be RAIN or defrost condensart
sorry i could never even guess the water gravity effects from any car made from fire wall to rear of care, gee hills even change that.
learn to do deeper inspection of all carpets there.

bad door gasket
or last drove car with say a bandanna hanging out the door.
a 1 time event,nobody can guess ever.
and allowed rain to go inside any car.
or windows were not fully up.

If it smells like anti freeze your heater core is bad. If it's just water then your windshield or doors are leaking.

does your car have AC.... ? ac problems can make a eggy smell also a damaged catalytic converter do the same. eggy smell can be the gas from the ac leaking out. you would need to have this check as it can do harm to your lungs..

Depends on where the water is coming from. The 2 most often causes of water buildup is either the heater core is leaking or the AC condensate drain tube is blocked. If the heater core was leaking, you'd smell antifreeze or see steam coming from the vents while driving. The AC condensate drain tube lets condensation water to drip overboard from the housing. This tube is on the bottom of the AC case on the firewall side under the hood. Sometimes you need only pinch it to open it to drain out the water buildup..

Hi when I work for the Honda dealer 15 years ago We found that when a passengers side is getting wet , My best guess is you have air conditioning in your car. I would bet you the problem is the ac drain hose is clogged, it is on the passengers side under the dash, if you look up where you're feet would be just follow the rug up and you will see the hose remove the hose, be careful removing it from the condenser nipple because it is plastic and can break , use an air house and blow any dirt and debris that maybe clogging the hose . When you remove the hose have a Cup or small bucket to catch any water that's remaining in the condenser , This is a common problem . Once you have those cleared and the condenser cleared the problem should stop. Remember to put the drain hose back on , ps you do not need to put a clamp on the hose it is not under any pressure, after you fix the problem I would remove the seats and pull the rug out and hang it to dry, wipe the floor of any water , you may want to put a fan in the car to dry it out, because if you do not get everything dry your car will start so smell like mold and mildew, and the floor of you car will start to rust up, so get it dry, I hope this helps, I promise you that that's where the waters coming from if you have air condition, just remember water gos down hill not up. Let me know how you make out.

sound like a bad heater core! the heater core is like a small radiator that is usually locaded in the dashboard on the passenger side. now if the leaking is really bad you are going to see water dripping by the front passenger tire or if it gets really bad it may leak inside the car. in order to fix this problem the HEATER CORE must be replaced. good luck

the eggy smell of sulfur is from the catalytic converter needing to be changed. This is a part of the exhaust system.

First see if coolant level is full. Do you get a funny smell &/or film on windshield when heater defrost is on? If no to all most likely plugged evap drain for a/c need to unplug so it will drain outside the van. If yes to any you have bad heater core.

Check the drain of A/C condensator, its possible that is clogged; check underdash passenger side.

Good luck.

drill a hole through the floor as a quick fix ,if it gets in let it out ,then check for the leak ,try under the firewall where the AC drain pipe is ,it could be the same pipe for drain water coming in from air intake vents