Is it ever normal for a new bath to drain really, really slowly?

[Christophe73]

Hi - I have just had a bath replaced during a bathroom renovation and the plug is now in the centre of the bath rather than at the end. It also now has a pop-up waste. The bath used to drain normally but after replacement, the bath drains very, very slowly, even when I unscrew and remove the pop-up. My builder is telling me this is normal due to the smaller pipe but it doesn't seem right to me. Could it be the slope? I was just wondering if it is ever "normal" for a bath to drain really slowly (as in, 10 minutes to empty the bath).

 

[Ric2013]

It can be perfectly normal if the waste pipe is somehow blocked.

Why has your builder used a smaller pipe anyway? 40mm/1.5" is standard for a bath - what's he used?