You will need to check with hdb to see if the plans for that bathroom include the moisture barrier found in wet bathrooms. If so, then, provided you are the owner of the flat and all relevant paperwork & permits have been filed then it should be okay. I'm assuming there is already a floor drain in the bathroom.
SOME PEOPLE TRY TO TURN BACK THEIR ODOMETERS. NOT ME. I WANT PEOPLE TO KNOW WHY I LOOK THIS WAY. I'VE TRAVELED A LONG WAY, AND SOME OF THE ROADS WEREN'T PAVED. ~ Will Rogers