This is a water tank 970mm X 610mm X 650mm high (38inch X24inch X 26inch high). Not sure what the BL50L on the lid means but it the normal size used in a 4 bed house. I had been using it as a sump when wet cutting tiles, hence the chalky mess which will easily wash off but I did not have access to water when I was clearing out my lock up. It is water tight apart from the obvious plumbing connections. It comes with the lid.