I'm doing some plumbing work in my house and I have a choice to make. My new tub is within 3 feet of 3/4", 1/2" and 1/4" copper supply lines for hot and cold. To make a long story short, the builder of the house ran the supplies through 2 reducers for some reason and had the 1/4" supply line going to fill the tub.

I don't want to re-use the 1/4" line because it took too long to fill the tub. But I don't know if I'll experience much difference between the 1/2" and 3/4" lines. In a perfect world with no loss, I figure all 3 would be the same flow rate, just different pressure due to the diameter changes. But in the real world, I don't know how they compare.

It will be significantly more work for me to hook up to the 3/4" supply line due to location (in a wall but tight against the drywall on the other side). I'm not sure how I'll cut and solder without making a big mess since it is hard to get to. The 1/2" is much more accessible. But if there is a big difference in how quickly the tub will fill, then I'd be inclined to use the 3/4".

So is there much difference between 1/2" and 3/4"?