I'm looking into a truck with air brakes so that I can pressurize a 200 gallon water tank, someone mentioned downsizing my truck and going with a water pump,  is anyone familiar with this system? I'm pulling a TK-50 putz. 

The last company I worked for had line pumps set up both ways. Air will give you lower water pressure than a hydraulic powered water pump, about 1/2.

Now if  your concrete pump is down [engine won't run] you will be happy with the lower/air over water system. When the hyd/water system is good to go it is the champion by far. I am not at all familiar with Ed's electric water pump set-up. Perhaps it is better yet????

For operator satisfaction the winner was the hyd/air set-up. 250psi water made clean out a snap and made short work of safely cleaning out 2 & 2 1/2 inch system

I'VE RUN TRUCKS BOTH WAYS AIR AND HYD. BOTH CAN FAIL IN DIFFRENT WAYS, SO WHY NOT HAVE THE BEST PRESSURE (HYD.).  

Look at getting a flat bed truck and put a 150 gal. plastic tank from Tractor Supply $200 get a 12 vdc pump $90, if you have a generator get a one inch line pump from Harbor Freight 120 vac $50. You can use either one to transfer water. We use 12 vdc and 120 vac on our trucks with a pressure washer. Keeps everything clean!!!!!!!!!! Clean pumps run better.

if you are going to go with a plastic tank get a 300 or 400 gal. you cant have too much fun or have too much water

Big Ed Thanx for the info, would you happen to have any pics of your set up?