
Since you're playing on survival mode, there's no way to revive the dweller. Did you change timezones or reset the clock or something? If it was a bug, it may have been related to your phone's internal clock. Once you recall a dweller, the exploration window should say something like "Returning to Vault Xh Xm". So, either you didn't successfully tell them to return, or some sort of bug occurred. Dwellers don't take damage while returning, and therefore don't need to use stimpacks and can't die. However, it sounds like you called your dweller back before they died. Always send explorers out with pets, even if the pet's buff doesn't help them explore. If you send them with a pet, then the pet brings the stuff back. If you send out a dweller without a pet, and they die, then you lose all your stuff. It got wiped from over 50 to 3 at one point, but we were able to rebuild. Seal the buckets and carry them to the surface as needed.I've been playing survival mode for a while, and have a vault of 90 dwellers. It isn’t ideal, but it is an effective way to keep your shelter safe and sanitary. Another option is to use small plastic toilets or buckets.You may not be able to get clean, running water in an emergency, so you may need to install an expensive system of tanks, pipes, and filters if you want more comfort. Many shelters do not feature running water, so a regular toilet isn’t usually an option.You can also try joining the pipe to the air pump’s ventilation pipe. You may need to dig through the dirt so the pipe exits above the plastic canopy over the entryway. To install the ventilation pipe, run it through the nearest entryway, if possible.A good location for the toilet is near the exit furthest from your sleeping quarters.

You will need to install a ventilation pipe, running it from the toilet to the surface. The most efficient way is a composting toilet, similar to what you would see in an RV. You have several options for installing toilets. Set up a toilet in a separate area of the shelter.
