When choosing a vacuum tank size for septic pumping, grease trap pumping, car wash pit pumping, or other industrial vacuum tank jobs, there are several factors to consider. Septic tank size, route density, proximity to dump site, local DOT requirements, CDL or non CDL drivers, GVW of chassis, and cost. 

 

In your region, what is the typical septic tank size? Some see 1000 or 1500 gallon as typical, while others regularly see 500 gallon tanks. If 1000 is normal for you to see, you likely want a 3600 gallon vacuum truck to be able to pump three septics, so you have some headroom for overages. If 1500 is more typical for you, you would want a 5000 gallon septic truck to pump the same three tanks. Or perhaps you are in the mountains and need a 4×4 to get one 500-750 gallon septic tank pumped in a day- a small 4×4 would do the trick. 
 
The route density question is really about this: How many tanks can you pump before needing to dump your septic truck? If your route density is great, you may want a larger septic pump truck to accommodate more septic pumpings before needing to go off-route to dump. 
 
Conversely, if you are never far from a dump location, a smaller vacuum truck may be what’s best for you. 
 
Some local DOT requirements enforce Federal Bridge Law, while others do not (requiring those regulations only on Federal Roads). Knowing what your local DOT requirements are is important in regards to: Federal Bridge Law, tanker endorsements, air brake endorsements, etc. 
 
Do your drivers have CDL licenses? If not, your options will become more limited. Generally, you can not get over 1600 gallon vacuum tank on a typical vacuum truck before getting over the 26,000 GVW CDL requirement. And even then, you will have tanker endorsement needs, and possibly air brake endorsement needs.  
 
Your chassis choice will determine maximum tank size, as well as how heavy the product you pump. A small F550, RAM or Isuzu will be limited to around 1000 gallons of waste hauling, under 26,000 GVW chassis will be limited to around 1700 gallons of waste hauling, 33,000 GVW around 2500 gallons, anything larger and you will need a tandem axle chassis. Tank size and chassis choice will greatly affect the cost of your new pump truck.  
 
In summary, there are MANY factors that will determine what tank size is best for your needs! There is no “one size fits all” solution. FlowMark sales staff is uniquely qualified and experienced in helping you to determine the best truck for the job!