Treating collected rainwater

[Horsefly]

My son now has a place that collects rainwater from the roof and gets stored in tanks for the home. Does the water need to be treated with chlorine or the like periodically? The water is used for everything in the home. The tank sizes are 2500 gal. capacity, 4 of them in series I believe.

[MadHatter]

Not if it's filtered right, before you drink it.
If tanks are above ground and light can penetrate them, then it's probably a good idea, otherwise algae will grow.

[Draco]

He should run it through a particulate filter, then a carbon filter and then a UV filter. That should pretty much take care of any problems.