Phildirt, the tile tape I was referring to has nothing to do with bathrooms, its ag drainage tape used on plastic tile lines, anything plastic it will stick to, we buy it by the case rolls of around 24 or 48, they are about 3 inches wide and the stuff won't rot or break down underground, in fact it will look brand new if dug up years from now, duct tape rots over time if left in the sun or underground, it usually lasts only about 4 years if you bury it. Prinsco, ADS, Agridrain can get tile tape for you, most any of the major drainage tile suppliers can get the stuff, there is better brands of it, I'm not sure what the name of the stuff is we get, I know it just by looking at it weather its the better or cheaper stuff.
It looks a lot like electrical tape only a lot wider and sticks better, its one sided and will stick to anything plastic, we use it on about anything because it will stick to itself so if you wrap it around several times to about anything it'll stick and stay put, wiring harness's on trucks we use a lot of it on those applications, especially if its outside in the elements, in the colder weather it still works fine and sticks if you use the better stuff, the cheaper stuff needs to be put over an exhaust pipe to warm it up first in order to get it to stick, thats why I don't like the cheap stuff, it'll stick if its used under water or if the plastic your sticking it to is wet or even muddy to a certain extent.
We've been installing waterlines this week along with drinking fountains and anytime we need to tape plastic or pvc pipe to anything to hold it in place, while we're backfilling, we use tile tape to do the job