Calgary in Western Canada was one of the first cities in North America to make the switch from iron to plastic pipes in their water and sewer systems. This economically motivated switch has led to cheaper housing for many of Calgary's one million residents and to millions of dollars saved for the city.

Calgary covers roughly 600 sq. km. and has around 300,000 households. The city has almost 4,500 km of streets with similar lengths of water, sanitary and storm sewers. Almost 40 percent of the pipes used are PVC plastic pipes. The transition to plastic pipes in Calgary began in 1980 and continues today. Roy Brander who is senior infrastructure engineer for Calgary Water Resources of the city of Calgary, explains: 

"The switch to plastic pipes is made for economic reasons. Plastic pipes cost about half as much to install as the iron pipes we were using for water pipes and sewers. This is due partly to lower material costs but more importantly to the fact that construction with the much lighter-weight material is faster." And Roy Brander continues:

"Naturally we had a choice to stay with the pipes we were using - first PDI (polywrap ductile iron) and later on YDI (yellow jacket ductile iron). However, YDI has ten times the corrosion-related break rate of PVC. So while the cost of installation of plastic pipes is about half, the cost of ongoing maintenance is less than one-tenth of YDI pipes and less than one-hundredth of PDI pipes. Given such a ratio, it was not a difficult decision at all." 

The Calgary switch to plastic pipes has resulted in two important cost savings for the city. Firstly, every house built in Calgary has been a couple of thousand dollars cheaper. This is because the average of 15 metres of pipe installed per house is hundreds of dollars cheaper per metre. Secondly, the new pipes have a much lower break rate: 

"The 1,400 km of 35-100 year old pipe made of unprotected metal has about 350 breaks per year. The 600 km of YDI pipe (all 25-35 years old) has about 30-40 breaks per year. The 2,000 km of PVC pipe have an average of only one break per year. Each break avoided saves about $10,000. I would currently estimate that the plastic pipes are saving us more than $1 million each year in avoided breaks," says Roy Brander. 

The switch to plastic pipes has affected almost all of Calgary's one million residents by providing them with cheaper housing and lower water and sewer bills. Furthermore, the plastic pipes installed 25 years ago are still working flawlessly. Hence, it looks like the plastic pipes have come to stay. As Roy Brander puts it: 

"Several percent of the plastic pipes have been installed long enough for us to be certain that the PVC pipes continue to provide faultless, near-zero-break service for decades. We are thus able to state with certainty that the long-term payback of switching to plastic is very high. To call us satisfied would be a gross understatement. I would call it the single best infrastructure decision the water & sewer department of Calgary has made in its history!" 

Facts

Since 1983 less than one percent of water and sewage installation in Calgary have been YDI or other metallic pipe
 
Since 2003, PEX plastic has been used for water service pipes in Calgary, now providing service to some 30,000 homes