Ideally, yes. Any organic matter that enters the storage tank contributes to algae growth. The goal of filtration is to keep as much organic matter and debris out of your rain tank as possible. The cleaner the water is going into the tank the better.
The simplest filtration device is a downspout screen filter. This device is installed on the side of the building and designed so that the rainwater, and not the debris, passes through an angled screen. The device is designed to self clean but periodic maintenance may be required. This filtration eliminates sticks, leaves, pine needles etc.
Another option is a vortex filter. The device spins the water outward and the debris falls through the main body while the water is directed to the tank.
Basket filters can be installed directly into the rain barrel or tank. These filters need to be continuously monitored to ensure debris does not build up.
The goal of these devices is to divert the dirtiest water from your storage tank. The first water that falls on the roof after a rain “pre-washes” the roof and picks up the majority of accumulated contaminants. This water is directed into a separate chamber and away from the tank. First Flush devices can be helpful in reducing harmful pathogens.
The regulations vary from province to province. In Alberta for example, harvested rainwater can be used for sub surface irrigation and toilet flushing. Check with your local authorities to determine the allowed uses in your area.
No. These filtration systems take out only large debris. Any pathogens in the water pass directly through these devices and into your tank. A separate water filtration system must be added to ensure any pathogens in the water are properly neutralized before drinking or showering in the water.