Break rates for pipe materials
Water main breaks are an everyday occurrence in North America, with over 800 breaks reported daily. One of the major contributors to this problem is pipe material. The National Research Council of Canada conducted a study on pipe break rates and generated findings that point to PVC as the material of choice and the answer to the problem. PVC pipe has the lowest break rate and the lowest overall failure rate compared to cast iron and ductile iron pipe.
These figures were produced from a survey of many pipe installation/replacement businesses. It also asked respondents to identify the most common failure mode by selecting from one of the following: corrosion, circumferential crack, longitudinal crack, leakage at joints, fatigue or other.
The average expected life of all new pipe of all materials was 79 years with a range of responses from 30 to 200 years. The survey measured the failure rates of the following types of pipe: cast iron (CI), ductile iron (DI), PVC, concrete pressure pipe (CPP), steel, and asbestos cement which is no longer installed in the US.
The survey requested the respondents to list the number of failures per year to five years, broken down by pipe material. The desired focus was to examine the year to year variations by pipe material. A single utility might have large year to year variations, but if the number of utilities samples is sufficient, the year to year variation is small. The following graph shows the failure rates by pipe material over a five year period.
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