We’ve already looked at what to do when a plumbing line inside the house freezes, but when the problem lies with the water inlet pipe, the situation is altogether more complicated.

The risks involved in thawing out this pipe range from water damage to a fire, but doing nothing at all is just as dangerous: the frozen pipe may burst and flood your basement.

Who is authorized to do the job?

First, find out what your municipal bylaws say. Many administrations require that the thawing operation be entrusted to a certified pipe mechanic who is a member of the Corporation des maîtres mécaniciens en tuyauterie du Québec (CMMTQ) and, if electrical devices are used, that the work be supervised by a certified electrician who is a member of the Corporation des maîtres-électriciens du Québec (CMEQ).

The Régie du bâtiment du Québec does not require contractors to be licenced to thaw out pipes. Although the task falls naturally within a plumber’s competencies, not all plumbers invest in the necessary equipment. You can also call on a company that specializes in unblocking drains and other pipes; they have developed expertise in thawing pipes by electrical means. If plumbing or electrical work ends up being needed, however, they will have to call in specialists.

What you need to know before calling a contractor

1. There are two procedures for thawing out pipes:

  • Hot water or steam

    Pros: Can be used on all kinds of pipes; no fire risk.
    Cons: Can take a while; may lead to water damage.
  • Electric

    Pros: A fairly quick operation.
    Cons: Cannot be used on non-metallic pipes or pipes with poor electrical conductivity; if thawing intensity is not properly controlled, can damage pipes and cause electrical wiring lying along a plumbing line to overheat, resulting in a fire risk.

It’s therefore a good idea to know what type of pipe you have before calling a contractor. You can find this out by looking at the base of the water inlet pipe.


2. A good contractor will:

  • Conduct a preliminary check to see whether there could be an electrical current leakage into the plumbing.
  • Have sufficient liability insurance.
  • Use an electric pipe-thawing machine certified by a recognized standards organization.
  • Check, and reduce if necessary, the intensity of the current applied to the pipe to eliminate any risk of overheating; a lengthier thaw period is preferable to a short, intense period.