When looking for a vacuum pump there are several questions that you should be considering. First you need to establish weather or not you need a diaphragm pump or an actual vacuum pump. This question can be addressed by knowing the following:
Vacuum Pumps: What You Should Know
Pumps for Car Wash Waste Pit Removal
One of the most popular pumps for waste pit pumping is the Mud Sucker 2FA-M Series. With a 20 GPM transfer capability this pump is great for car wash waste.