I was always told growing up to leave the toilet lid down when the cat was around just in case the cat jumped into the toilet and drowned. Now I realize how absurd that is, but I was just wondering if maybe I should do the opposite? I was just thinking how if I’m away from a few days I’ll leave my cat a weeks worth of dry food and water, but I was wondering if there was ever an emergency where I can’t get back to my house, should I leave the toilet lid up just to give him a backup of water just in case? He sometimes is able to somehow knock his entire water bowl over on occassion, so would this be a decent thing to help him drink water just in case?
I’d worry more about the possibility of the cat falling in than about the possibility of him spilling his water. In your place, I’d be more likely to add a non-tipping water dish as a backup.
(But, really, if we leave the cats for more than overnight, we get a petsitter. I’m a worry wart about them.)
Little kittens can get stuck in the toilet bowl. When i foster kittens i am careful to leave the lid closed. Big kittens and every adult cat I’ve seen can get out of the toilet bowl.
(And yes, I’ve seen kittens leap into the toilet bowl as i scoop their poop into it. The ones big enough to get in that fast are also big enough to get out, but they are pretty unhappy when they do.)
When i go on vacation, i give the toilet a couple of extra flushes and leave the lid up, just in case the cat overturns all the other water I’ve left it.
One of our 6 cats is a bobtail dwarf Highlander (a cross between Desert Lynx and a Jungle Curl) named Ollie. She’s an over-confident, over-inquisitive mess of a cat. Though Ollie’s the smallest of our clowder (1 year old and still looks like a kitten), she is by far the bossiest. She takes no guff from any cat (or human), and when she gets roughed up by the others (often), she just comes back for more…and more, until she wears out her opponent. Her battery never discharges. If there’s trouble to be found, Ollie finds it. Cute as a button, though. 
I’ve been woken many times in the early AM to Ollie’s cries for help. One time I found her swinging by a claw from a floor lamp pull cord (she must have leaped 4 feet to reach it). Another time I found her inside the washing machine (she must have pried open the door-top to gain entry). Another time I found her in a wall recess, adjacent to the ceiling (how she got in there, I don’t know). Yet another time, I found her swimming inside the toilet bowl. It’s taken great effort to Ollie-proof the house.
So, if your cat is anything like Ollie, I recommend keeping your toilet lid closed, with a heavy weight on top.
My cat could get out of the toilet if she ever fell in, and she is capable of drying herself if needed. For that reason I left it open (and clean) when I traveled, and would leave it open usually when I went out as an emergency water source for her.
However if she was unable to get out, I would close the lid to prevent the horrors that could be. Though that would be either a very young kitten which would not have free run of the house (and with a momma cat I’m pretty sure the momma would rescue it), or a very elderly cat.
If you trained your cat to use the toilet instead of a litter box then I suggest you leave it open.
Why not just get a bowl that can’t easily be knocked over?
Agreed. Asuka, do you have a trustworthy friend who can just check in on them briefly once a day?
I believe the OP is talking about a modern American-style toilet that doesn’t knock over, not those silly English chamber pots that can. 
Junior is absurdly picky about his water sources and I hate cleaning those water-circulating cat fountains, so he has an Aquapurr. It means he has all the fresh-from-the-tap water he wants. I still leave the toilet seat up when I’m away overnight, though, because I am an anxious creature and worry about the batteries dying at the worst possible time.
Joining the chorus.
I’ve had an apparently entirely healthy young cat take sick one day and be in danger of her life if not treated by the next day. Get somebody to check on the cat daily. They can refill the food and water dishes.
And I also join in the chorus of getting a water dish that’s harder to knock over. Try a wide-based dog water dish.
If you’re only away one night, unless the cat has known kidney issues I wouldn’t worry about it.
You are entirely correct; it is an irrational response to an irrational fear.
Leave it up; I haven’t given my cat water in a bowl in over 5 years; she helps herself from any of the 4 toilets around the house. That water is arguably cleaner than a cat/dog water dish anyway. The day she A) falls in and B) can’t get out is the day she’d be ready for the human equivalent of a nursing home.
We have wide-based water dishes. But it’s free to ALSO leave the toilet open for the cat, just in case.
My toilets are always closed except when they are being actively used. I use things like Sani-Flush and other bowl cleaning additives that make the water dangerous to animals. Whenever I leave for a few days, they get an additional bowl of water to augment their gallon waterer. On top of all that, I have a nanny-cam in that room so I can monitor the situation remotely. If they knock over the water I can call a friend with my house key to refill/reset things.
She hasn’t even left a water bowl for the cat in months. Cat prefers the dog’s bowl & will nap on the dog’s bed on the floor, or in front of the fridge, by the warmth, also on the floor. My baby gurl will be seven on Wed & mostly leaves the cat alone, 'cept for an occasional sniff or come to check out what’s going on when I am playing with her.
However, after next week, the cat will need her own water bowl again as she will spend as little time as possible on the floor. Offspring #2 comes back home from college with her undertrained 1yo whirling dervish of a pup.
My cat has a dog dish for water, and gets a big mixing bowl of water in the bathtub with the tub drain closed if we’re away. Or a catsitter if it’s more than a day or two.
A cat that may drown in a toilet bowl, is not a very agile cat.
I would not worry about the Cat. It is probably plotting your death anyway and just wants to eat your face. Pretty normal cat behavior.
I remember after 9/11 many people couldn’t return to their homes, even to get their pets. Having the extra water available in case of emergency, even something like a car accident, where you’re unconscious for a time an unable to get someone to get to your animals. My dogs have an indoor water bowl, and a couple 5 gallon buckets outside. My horses have a creek and a trough. There have been horses that died of dehydration because the auto-waterers failed and no one was checking them daily.
Better safe than sorry.
StG