My HDB estate is currently undergoing Home Improvement Programme (HIP). HDB units (especially those just renovated their houses) who do not opt for toilet/bathroom upgrading must undergo a compulsory water proofing test. According to HDB, the toilet floor will be flooded to 2.5cm of water for 4 hours. If there is leak to the ceiling of the flat below then the water proofing test has failed. We all know HDB flats are strictly residential. I can't think of anybody who bathe for a continuous long period of 4 hours and able to flood the toilet floor to even 1cm of water. The diameter of drainage outlet is so much bigger than diameter of shower tap. Water outflow is anytime faster than water inflow. Is the criteria for HDB water proofing test a little too far fetched and UNREALISTIC. Also, are water proofing membrane done by HDB authorised contractors designed to withstand 2.5cm of water for 4 hours; because I never hear it mentioned when I talked to renovation contractors and it was never even in the terms and conditions. I have people in other forums insisting this is standard test. Since this criteria was never mentioned or noted in renovation contract, can we assume it is standard HDB requirement and so is IMPLICIT in the agreement. And suppose water test failed, can we get contractor to compensate/foot cost of repair ? I hope HDB, MND, URA, building professionals, and knowledgeable people can kindly contribute, comment, and advise on this matter. Thank you. PS: I am not so IT literate and my friend help me post this article. If there is a proper forum to raise this issue, kindly help me port this over or do advise. Thank you.