In all brake bleeding procedures, a bottle is used to collect old and dirty fluid. I have seen some people who place the bottle on the ground below the bleeding screw (Picture A) while others may place it as high or even higher than (above) the bleeding screw like in picture B. Does it make any difference if you place the bottle below or above the bleeding screw? Does it affect the bleeding?
You should keep the bottle BELOW the caliper level, so as not to leave air in the caliper while bleeding. Air in the line itself won't matter too much as it travels to the bottle because of pressure (this is due to surface tension against the sides of the tube). If you have any pressure within the lines, such as back feeding because the bottle is higher, the potential is there to not allow all of the air to escape from the caliper. Placing it on the ground should help alleviate this issue.
Another consideration here is to ensure you have some fluid in the bottle when you start the bleeding process. Then keep the end of the tube submerged in the fluid. This will help from sucking air back into the tube if the pedal is released prior to getting the bleeder nipple closed.
The benefit of positioning the bottle higher, like in picture b, will be that you keep fluid in the pipe near the bleed nipple rather than air, so you are less likely to be able to draw air back into calliper that way.
