The reason why the water trap is small is because the larger the trap, the more expensive it is. Think about the lab quality water trap at 1 liter size, shooting up past $50. 2 liters size goes high in to $70 and $80. That costs brings the system way up. Smaller 4oz or 6oz trap keeps the system economical, and still provide the sufficient 18inHg support.Yesterday I tried mityvac water pump and it worked well. Today, my EQ just wasn't good enough until I ran into water trap being too small to continue pumping. Why did they make it so small? I can't even properly release the pressure with the pump gun when its so full.