I am about to replace a mixer tap the old one has been plumbed in with 15mm push fit fittings see below;

http://www.screwfix.com/p/yorkshire-...ails_container

The new one has flexible tails, so just a case of cutting the pipes at some convenient point and tightening the compression fittings on. However, this is my first experience of these push fit fittings and I was wondering how careful I need to be, will causing them to twist result in leaks or are they fairly robust?

Richard