We have a rainwater collection system which brings water from the roof through the gutters, down large outside pvc pipes into the filtration and collection system indoors in the house basement. The highest part of the system is up three stories; it will take a pro to check that. But I want to be able to test the flow from eyeball height off the ground into the system by running water into the pipes and then watching at the first collection tank to see what comes out and how fast. Currently we are not getting the water into the system that our rainfall should produce; there must be a blockage somewhere in the gutters or downflow pipes. (There is a filter there to catch any big stuff.) The way I can think of is to install male hose connectors (forget the plumbers name for them) into the pvc pipes at eye level. I could then attach the hose there, run it and see what happens/catch any debris at the lower leve. It would eliminate the lower level when inflow is too slow. As for blockages above that, I know I need to call a gutter guy or plumber. But: how do I attach or insert that hose connector?

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Typonote: Pleads four give ottocorrect miss steaks!

you either drill and tap a hole to screw in a 3/4 inch male by 3/4 hose adapter or if the pipe is large enough you can use a saddle fitting.

from my experience with gutters the clog is usually right at the beginning of the downspout up in the gutters.