Spray on the repellent (one brand is DEFY Masonry Chimney Water Repellent; $35 at saversystems.com) with a low-pressure,
garden pump sprayer (Photo 3).
Mrs Telling has been forced to live upstairs for the past three years to escape raw sewage which backs up the toilet and bath while an overflowing drain in the
garden pumps human waste into the garden in heavy rain.
Some come complete with a pump, but there are good suppliers of
garden pumps for all sorts of purposes, including the construction of water features.