Just woke up to the fill valve in our toilet not shutting off. I'm pretty sure it's shot so I ordered a new one which should be here tomorrow. We live in a really old house and the shut off valve is rusted so the only way I can shut it off is the water main by the street.

My big fear is the septic tank. The toilet is running at max flow, will it overflow the septic tank say by now and until late evening tomorrow? I read some say it goes straight out into the drain fields and some say it could cause a septic system to collapse. We've never had issues with our septic in 25 years so I don't want this to cause a problem.

The main question is, is it okay if it runs a while or do I need to cut the water to the entire house?

>>2920219 (OP)
bump

>>2920219 (OP)
I'd shut off the main water valve overnight and then open it again in the morning to do your morning routine activities, then shut it off again, go get the parts you need and replace your messed up valves (all of them, not just the fill float in the toilet) before turning the water back on.

>>2920219 (OP)
I've had toilets stick open all day and they never caused any damage, but maybe I got lucky. I'd say kill the main line, if you are worried. Have you tried some heat and penetrating oil on the valve and GENTLY working it back and forth? It will probably begin dripping and you'll have to deal with that, for a few days, but you might be able to shut off most of the water going to the toilet.

>>2920376

>>2920219 (OP)
replace the shutoff for the toilet while you wait for parts...
you can get replacement valves at any hardware store, they even make sharkbite versions

>>2920219 (OP)
Houses are fitted with obsolete compression valves, and should be upgraded to quarter turn ball valves. Shut off the main, put a pan under valve to catch water, use non marring 13/16 and 15/16 wrenches to remove old valve, use a puller to remove the old pipe compression nut, use emery cloth or any black silica sand paper to sand pipe, use a de-burring brush to smooth out edges of copper pipe, slide new nut on, put one layer of plumbers tape around nut, slide on new ball valve, fasten with wrenches, replace toilet fill valve, set float of fill system just under water level of over flow pipe, turn on main.