I bought a house and found out too late that it appears the entire upper floor is supplied from one small pipe. So if you flush the toilet or wash your hands while someone is in the shower, they get burnt (cold water pressure drops, only hot water is left coming).

I know nothing about plumbing, but I was wondering if I have any options to fix this. Replacing the piping seems out of the question as it would require opening walls, floors, the lot.

My main concern is the shower. If the sink flows slightly less, or the toilet needs longer to fill back up - that's fine with me. But I'd like to take a shower without warning everyone not to use the toilet.

But what, exactly, are my options?

I bought a house and found out too late that it appears the entire upper floor is supplied from one small pipe. So if you flush the toilet or wash your hands while someone is in the shower, they get burnt (cold water pressure drops, only hot water is left coming).

I know nothing about plumbing, but I was wondering if I have any options to fix this. Replacing the piping seems out of the question as it would require opening walls, floors, the lot.

My main concern is the shower. If the sink flows slightly less, or the toilet needs longer to fill back up - that's fine with me. But I'd like to take a shower without warning everyone not to use the toilet.

But what, exactly, are my options?

Edit: Additional information: I'm on city water. The house is about 5 years old, so pipes aren't old. The previous owners simply put in too small pipes.