I learned (the hard way) that Teflon tape in not appropriate for threaded PVC fittings. It causes two issues: 1) It makes the male fitting larger and the excess volume in the threads can split the female fitting. 2) The Teflon lubricates the threads making it easier to turn the joint too much; these threads are tapered and turning them too far also results in splitting the female fitting. Better to use a thread sealant made for PVC, it is either hardening and non-hardening - use non-hardening if you plan to re-open the joint. Put a bead of sealant all the way around the end of the female fitting and let the male fitting push the sealant into the threads and fittings.

Yellow tape is for gas but works for water. Pink works great for metal pipe threads.