This particular tank,manufactured by Premier Plastics, is cylindrical and made of polyethylene which is a type of plastic that is CSA and NSF 61 approved for potable applications. It is designed to be installed above ground and can be purchased in a wide variety of sizes, from 130 to 5000 US gallons. These tanks come standard with a 16" vented access/fill lid but can fitted optionally with a 21" lid.
Premier tanks are built in one piece and are impact resistant and UV stable. They come with an 8 year warranty but can be expected to last much longer. Colour choices include dark green and black, the darker colours being preferable for water storage to prevent light infiltration which can encourage biological growth within the tank.
This next photo show several interior components more clearly. The larger white PVC pipe on the left is where the water flows in after it is conveyed from the catchment surface (generally a roof). You'll notice there are two elbows attached to the bottom. This feature is called a calming inlet and the purpose is to channel incoming water upward and prevent it from disturbing any material that may be lying on the bottom of the tank. Hopefully there won't be too much of this. Another rainwater harvesting best practice is to ensure that all water entering the tank is filtered and all openings sealed so that debris and unwanted pests can't enter.
Just to the right of the water inlet on the bottom of the tank is a submersible pump. Pumps can also be installed outside of the tank and for some applications gravity can be sufficient to get the water to where you want it to go. In this installation, you can see there is a PVC outlet pipe attached to the top of the pump. Although the picture doesn't show it, the outlet is intended to exit the tank through a bulkhead fitting near the top. The bottom of the pump is connected to a floating inlet assembly which includes the translucent blue ribbed pipe, filter and round black float. This ensures that the pump draws only the cleanest water in the tank which can be found just below the surface.
Although it is difficult to see, if you look back at the top image there is another PVC pipe to the left of the inlet. This is the overflow outlet which is absolutely critical to include in every installation to ensure that we don't run into problems when rain is falling faster than we can use or store it.