Yeah, depends on the amount of roots in my experience but generally agree it wouldn’t help. Honestly not sure if it will help at all but only reason I can see why they’d do it.

Could be you don’t see many if they are jetting the sewer as standard. Generally not the case in the UK and we’d only jet if there is a need to do so. Assume it saves money overall even if we need to pay again.

So if they need to get new footage I assume that’s because they can’t properly survey it?

Generally debris (from sewer collapse or silt), standing water and roots are the main reasons we can’t complete them. Jetting the sewers may help in some cases but roots can still be problematic even after that.

Water level is rarely due to sagging pipe in my experience as the surveyors can get through some water. It’s normally due to the sewer network being fully surcharged either due to storm events or operational issues.

Not in the UK. No idea what size sewers you’re talking about but never come across anything that does that and sewers being surcharged is often a reason for them being unable to complete the survey.

In the UK at least CCTV surveys often can’t be completed if there is a large amount of silt or ragging in the sewer. I’d assume in clean water pipes there would be similar issues due to tuberculation in older mains and this may be why they’ve avoided wheels