Two 19th century Town houses share 1800 square foot roof water run off. Water goes to a large 9" galvanized gutter then down a single 50 foot 5" galvanized downspout which conects to only one houses main drain and out 50 (under the house) to the street sewer. Being so old,4 story trees are constantly plug the wire mushroom strainer in the downspout. Other than weekly clearing of gutter wire mushroom strainer, IS THERE A WAY TO PREVENT HEAVY RAIN GUTTER OVERFLOW FROM SHEETING DOWN THE BACK OF OUR HOMES? Would those rain handler water dispersers installed on the back wall a few feet below gutter overflow in heavy rains? What is a maximum water handling solution? There is no basement water back up with the house drain to the street. It is rodded yearly. But the system, even kept clear of tree debris overflows in downpours?