While Dan Huggins is a busy man, his phone isn't exactly ringing off the hook.

Dan Huggins is the manager of water quality for the City of London. (Dan Huggins/City of London)

"This year we haven't been too busy compared to past years," he said. "We're a little below our average."

Huggins is the Water Quality Manager for the City of London. It's his job to make sure the water comes out of your tap when you need it and that it's safe and clean to drink.

Part of that work involves making sure the city's plumbing is in order, which can be a tall task anytime a deep freeze hits the city followed by a thaw, like the one we recently experienced.

Last week, temperatures plunged as an Arctic air mass stalled over much of North America, chilling communities like London so deeply thermometers barely registered -20 C during the day.

A week later, the frigid weather retreated with the advance of a spring-like warmth, melting the icy landscape into a watery slushy mess.

Those wild shifts in temperature can cause the ground to expand and contract, placing pressure on watermains and causing pipes weakened by corrosion to break.

This sinkhole at London's Oxford and Talbot intersection happened earlier this season and at 20 feet across, was large enough to swallow a car. (Dan Huggins/City of London)

It's something that's happening less often as the city moves to replace aging plumbing, which in some cases dates back to the 1880s in some sections of the downtown.

"Overall we've had a downward trend over the last 20 to 25 years as we replace and rehabilitate our infrastructure, but our main factor causing the yearly variability is the severity of the winter," Huggins said.

Last month there were 19 watermain breaks in London, about a third less than the 28 watermain breaks that had to be fixed during the same month last year.

The reason it might seem like there are more is because the city is making an effort to get the word out to drivers, to alert them about lane reductions due to underground work.

These old watermains were ripped out of the ground along Dundas Street as part of the Dundas Place streetscape revitalization project. (Dundas Place)

"Even though our watermain breaks are down this year, our communications have increased, so Londoners can be aware," he said.

One such watermain break created a 20 foot crater that buckled the blacktop at Oxford Street and Talbot Street. Huggins said crews worked overnight to repair the leak, fill the hole and repave the road, so it could be used by lunchtime the next day.

ROAD CLOSURE: Due to a watermain break, Dundas St is closed between Richmond St and Clarence St and one southbound lane is closed on Clarence St between Dundas St and King St. Crews are on site now completing repairs. Expect delays in the area. <a href="https://twitter.com/hashtag/LdnOnt?src=hash&ref_src=twsrc%5Etfw">#LdnOnt</a> —@CityofLdnOnt

Huggins said the city isn't just replacing old sections of pipe, it's also rehabilitating them in an operation by city crews that sounds akin to when a doctor places stents inside the arteries of a heart patient.

"It's very similar, yep," Huggins said. "The artery analogy isn't a bad one. People know that watermains get clogged."

Instead of ripping up an entire street, city crews will create a series of holes in the street to access the pipes underneath, then they'll scrape them clean and install a fibreglass pipe inside the old pipe to act as a liner.

Huggins said it keeps old cast iron watermains from becoming too swollen because of corrosion.

"When you have an iron watermain, it rusts and over the decades that rust grows inward reducing the carrying capacity of that pipe and that carrying capacity is greatly diminished," he said.