In article , joggerman.6606528
@gardenbanter.co.uk says...

I have two 1000 litre storage tanks which collect water from the roof,
and I then use to water our vegatable garden.

....

The water will contain whatever is washed off the roof, including bird
droppings etc.


In my enthusiasm I missed the volume of your tanks and didn't ask if you
have a bird-roosting problem on the roof.