Question about drowning and other forced damage in my 1-HP mod

I'm making a 1-HP mod (every damage-able monster and the player all have 1 HP) for a silly fun challenge. I removed fall damage because otherwise the Episode 1 boss level is impossible, but maybe I should just increase the threshold so any forced falls don't kill. Questions:

  1. Are there any places where the player is forced to take drown damage?

I vaguely remember a cage the player has to travel in, but I forget which level.

If so, how long do I need to increase the timer to in order to make the challenge fair?

  1. Are there other sources of forced damage the player cannot reasonably avoid (without cheats, exploits, etc)? Such as getting squeezed by moving walls, forced to pass through slime/lava, etc. I used to play quake a lot but I don't remember anywhere that the game just squishes you or tosses you into nails and expects you to take the hit.

For anyone interested in the silly mod:

Armor gives you a free hit: it blocks all damage, then goes away completely. It also rots away at 1 per second, so the armor amount you have is a timer on how long your protection lasts. I'm still tinkering with the right timers. I started at Green 15 seconds, Yellow 30, Red 45, but that feels too short. I might double them. Their original values of 100, 150, 200 feel too generous though? Armor is meant to only slightly break the one-hit rule.

Megahealth still gives you 100 health, but rots away at 5 per second. Might be too fast, but I didn't want it interfering too much with the mod's principle.

Normal health and quad damage serve no purpose. They remain merely to taunt the player.

Invincibility works normally.

Shub has 100 health, because for some reason I was winning the game instantly when entering End when she only had 1 HP. I dunno it kinda works: I think it's funny that she's the only one that cheats and has 100 HP, but a single rocket still beats her... the same rocket you pick up just before seeing her.

If anyone would like to try it out, I need someone to test this to make sure it's actually fully beatable. I've been playing to test it in concept, but I'm working long overtime at work so a thorough test from me will take a very long time.