The water was collected from the roof gutters.
Cistern no gutters.
This is a cistern i made from some pressure treated 2x6 material and a 55 gallon plastic juice drum.
The water might have been used by the household if there was no city water at the time.
Install standard size mesh gutter covers over the entire gutter that will lead into the cistern.
Rainwater harvesting is collecting the run off from a structure or other impervious surface in order to store it for later use.
It is more important that you have unrestricted flow into the cistern.
The cistern typically located underground may be constructed of various materials including cinderblock reinforced concrete or precast concrete fiberglass or steel.
Traditionally this involves harvesting the rain from a roof.
The rain will collect in gutters that channel the water into downspouts and then into some sort of storage vessel.
I got the used drum locally for 15 and the wood came from my scrap bin.
Cistern covers are 2 x2 and are cast in the floor.
I chose to use 2x6 material because i had it handy but if you choose to u.
If you join too many downspouts before they enter the cistern you could have a constriction that would be problematic.
Sweep all debris from the roof and gutters leading to the chosen downspout by using a broom.
Remember that the x section of a 4 pipe is twice that of a 3 pipe.