Temporary repairs can be made with rubber-coated tape or Goop, but to permanently seal a leak in a PVC pipe, use regular PVC adhesive and a coupling. The adhesive and coupling can be purchased at a hardware store or anywhere plumbing supplies are sold, such as home improvement store like Home Depot.
Choice of sealants at plumbers' disposal include plumber's putty, which comes in resealable container and usually require application with specific tools, like a putty knife, and thread seal tape, also called PTFE tape, which is made of polytetrafluorethylene. PTFE tape is available in several widths, and is completely waterproof. Teflon-based pipe-thread sealants are also available.