It’s unfortunate but in a new build the pipes for the heating system run through the walls.
It’s impossible to see where the pipes go so if l’m going to hang or fit something to a plaster board wall l always check with a professional detector to see if there are any pipes or electrical cables.

Unfortunately for the BT engineer they didn’t check and drilled through these pipes. It took a month for the home owner to release water was slowly dripping out and damaging the floor.

My job was to simply cover over the hole made by the plumber who mended the leak.

Leave that to dry then after a little sand down your ready to paint.