My kitchen waste pipe discharges through the back wall of the house. Until yesterday it used push-fit connections; one of these had given way and waste water has been discharging down the wall. I've replaced the lot with cemented and compression joints, but there's quite a bit of green fungus on the outer wall under where the pipe passes through. The bricks and mortar seem to be in good condition, but is there a recommended fungicide suitable for brickwork?
Thanks -