We've recently gone from a septic tank to mains drainage. Since this happened we are getting a slight sewerage smell in the bathroom and the shower waste 'gurgles' (for want of a better word). The waste connection goes straight to the mains so there is now a long uninterrupted run and I'm guessing to 'gurgle' is the water rushing down the pipe. I'm also guessing this rushing is breaking the 'seal' on the trap.

Is there any way that this can be remedied easily? If we installed an inspection ch