I'm having an issue with my toilet tank fillying extremely slowly, around 30 min to fill. There are 2 work arounds that seem to resolve the problem on a one time basis. First one is if I off the stop valve/supply vlave and then turn it back on, it fill rate returns to normal immediately. Second, if the slow fill is in process and I run the shower that is about 5 feet away, the slow fill problem disappears immediately. It's almost as if a slight pressure change anywhere in the supply kick starts the fill rate back to normal. Looking for some thoguhts as to possible causes.

I've already replaced the stop valve/supply valve so that is ruled out.

Since it does eventually fill and doesn't lose water, I'm pretty sure it's not the flapper. Also, the shower work around above wouldn't make any sense if it was a flapper issue.

I don't think it's the supply tube or float/overflow assembly because the work around above works. I've also tried jiggling the supply tube and float/overflow assembly during a slow fill and it does not resolve the problem. I would think if there was build up or blockage in these systems a wiggle or something would also be a viable work around. I also confirmed no blockage in the supply tube when I replaced the stop valve.

At this point I'm not sure if I should just replace the supply tube and float/overflow assemblies just to rule those out 100% as well. My hunch is that this is a supply pipe issue somewhere inside the wall. I just don't know if I should call my handyman or a real plumbler, and what should they be looking for.

Additional info that may be relevant. House was built in 1964, homes has copper pipes (not sure if it was ever repiped), stop valve/supply valve is brand new, float/overflow assembly in tank is about 2 yr old, supply tube is looks ot be within 5 years old.

Any help is greatly appreciated.

Tell me which ballcock you have and we'll get started. Back to you. Tom