I have recently had a problem with what is suspected to be a leaking cold water pipe in my bathroom set into the concrete floor. The bathroom is in a 20 year old extension with concrete floor,the rest of the bungalow is pre war with suspended floor. After having a new combi fitted 2 months ago i now have mains pressure going to the bath. I have had the pipe terminated (along with the hot and the rad pipes),termination is at the point where the suspended floor meets the concrete floor and replaced all pipes but this time running above floor level round the skirting boards. Therefore there are no remaining active pipes under the concrete floor. The leaking pipe has caused the water to rise up the internal block wall to a height of about 10 inchs and leave a wet patch visible on the plaster,the concrete floor appears to be dry to feel its literally only gone upwards??? Now the pipe has been replaced how long should it take to dry out before i can decorate and the wet patch will dissapear? I do have a dehumidifier but suspect how useful it will be in a bathroom which has to be used in the meantime.