Swimming Pool Soi42

Last month I was on my holidays and had 4 days in Bangkok. I had read about the swimming pool more or less across the road from Ekami bus station so paid it a visit. The entrance had a security kiosk ( manned ) that paid me no attention as I wandered in. There was a bloke doing lenghths ( suppose I should have asked him this question ) apart from that nobody else about. So my question is who owns this pool and how do you get permission for a dip? I was going to change and dive in as the change rooms were open but thought better of it as it could have got confrontational, not intentionally but things have a habit of escalating so didn't.