The downpipe filter speedy collects the rain water but filters out the dirt from the rain water it will automatically fill your water collection tank and will prevent it overflowing when full you do not need to dismount the downpipe when attaching the filter can be mounted in 5 minutes the distance from the wall to the downpipe does not affect how it works you can quickly change from summer to winter operation by turning the filter 90 ideal for downpipes with a diameter of 70 1