You are refering to "Water Towers," of which some can be factory manufactured models, other home-made. I've used a great many over the years of both types and even made some out of old 10000 gallon fuel tanks in Colorado on a large project. They can be made in many sizes to fit job requirements however, but most are in the 8-12000 gallon capacity range these days. Most are portable with wheels and can be hydraulically raised or lowered for quick hook up and use. Klein and Mega are two major makers, there are a lot of others. These towers were not too common untill dust control became a major issue with various government entities in the eighties. Now, a job site without one or two is rare.
Story. On a jobsite up east a compatriot of mine -- who shall go un-named -- had his mechanics set up a rental tower for a road job in New Jersey. They hooked her all up and opened the feed water valve to fill it. The water wagon driver set his rig under the pour spout and when all was ready, he opened the 12" valve there so as to fill his wagon. Taking the time to smoke a faggot, he heard a sudden loud groaning noise and looked up to see the water tower implode. Not knowing what else to do he ran like hell to tell someone about this strange event. Investigation reveled that the mechanics had forgotten or overlooked removing the pipe cap on top of the tank and installation of the vent valve. This of course, caused a huge vacuum inside the tank as the water rushed out and it simply collapsed. Very costly.
Nother story. On road job next to one I was on in California, that contractors mechanics also forgot to remove the pipe plug on top and they didn't properly install the float valve. When they turned the hydrant on, the tank filled, then blew out one end of the tank, nearly drowning the mechanic who was still standing there putting his tools away in his truck.
On one of my jobs in Colorado, our shop-built tanks had to be raised by a crane, then the legs pinned in place. My boys got the tank up, had it all plumbed and everything, started filling the tank and were feeling pretty good about life, till one end of the tank slid down and the whole thing went toppsy-turvey on it's nose. Oops! Have to put ALL eight leg pins in fellas, not just six! That tank was ruined and we had to build another one to replace it.
In Kentucky, we used a 40,000 gallon tank that came from a coal tipple. Propped it up on a hillside and ran the hose down to a load-out stand pipe. We needed another one for another mine site so I had an old Klein water wagon tank towed about 25 miles from a reclaimed mine to where we needed it. My welder built a stand for it and we hooked up a 12" water valve. Both worked great, but the water wagon hands weren't very happy as they no longer had any time to goof off. Their water wagons filled in about 5 minutes and off they had to go.
Lots of good memories with water towers.