How can I clean this mould behind kitchen counters?

Emily_Joy

We have seen the same after pulling the dishwasher and the washing machine away. It is likely to be just combination of the lack of ventilation and condensation. Get any black mold killer (we used bang, but it doesn't really matter) better with bleach. Spray it on the mold. Ventilate very well. Wash it off (wearing gloves). Let the wall dry out. Then check the condition of the plaster.

cerebus

Is the boiler leaking? Condensate pipe solvent welded correctly ? Any pipe leaks , past or present?

Thats my first guess looking at the pattern of the mould 

MikeJXE

Emily_Joy said:

We have seen the same after pulling the dishwasher and the washing machine away. It is likely to be just combination of the lack of ventilation and condensation. Get any black mold killer (we used bang, but it doesn't really matter) better with bleach. Spray it on the mold. Ventilate very well. Wash it off (wearing gloves). Let the wall dry out. Then check the condition of the plaster.

I agree bleach is the answer, spray it on and leave over night it will be gone next day

take care with health and safety issues, keep an air flow