Maybee you should draw the sewer like the room, with a 'full' back wall and the fron wall cut away. Now it looks like windows on a covered bridge, or something. Sewer-pipes that size is made of concrete, so you should ad some texture and joints, something like this:

And next, the drain-pipe from the shower, why does it come frome the wall? shouldn't it come from a drain in the floor?
And to make it more intresting, you could always ad a girl showering or something...

And next, the drain-pipe from the shower, why does it come frome the wall? shouldn't it come from a drain in the floor?
And to make it more intresting, you could always ad a girl showering or something...