External auxiliary potable water tank recommendations?

Either the potable water plastic drums in 15, 30 or 50 gallon sizes for at the trailer and then one of the water bags for easy storage when not in use.

You can sometimes find the water drums on Craigs List from different food business. There's 25 on our CL from a baker for $20 ea.

Then get a cheap water pump. This could be a cheap 110V from Harbor Freight to a little pump that goes in the end of a drill motor from any hardware store.

Bill