The section of the city's public works department that handles calls from Copenhagen residents to deal with rats received nearly 700 calls in July. That is a 26 percent increase from last year at the same time and, with apologies to the Chinese, 2013 is shaping up to be the real ‘year of the rat’ in Copenhagen.

“It is a very hefty increase, which we take very seriously, because rats represent a major health risk,” Morten Otkjær Thune from the city’s public works department told Politiken newspaper. “Rats carry germs that can make people sick.”

There are an estimated 100,000 rats living in the sewers under the capital city. Although there are no indications that the number is growing, the constant construction all around the city and the deteriorating condition of the city’s ancient sewer system encourages the rodents to leave their underground lairs and drop in on unsuspecting homeowners and businesses.

"Nearly the entire city is dug up, and every time you dig, you open up old sewer pipes filled with rats,” said Thune.

City rat, country rat
But it's not just in the capital. The rat problem is growing around the country. The cost of battling the nasty vermin has increased 50 percent over the past five years and has chewed nearly 92 million kroner out of council budgets.

Governments are not alone in battling the rats. Homeowners and housing associations are increasingly paying costs that can reach into the hundreds of thousands of kroner for private owners and millions of kroner for homeowners' associations that need to upgrade sewers

A homeowners' group in northwest Copenhagen is replacing and rehabilitating private sewer pipes in the area to combat the rats. The bill for the association comes to three million kroner on top of the 1.5 million being paid by the group’s insurance company. The 149 apartment owners are paying increased residents' fees, and seeing other renovation projects put on hold while the rats are dealt with.

“The pipes are so old, the insurance company will only pay part of the cost,” said Carsten Heyn, the head of the homeowners' association.

Price keeps growing
The cost to homeowners is expected to rise. When the city renovates the main sewer lines, the individual lines connected to private homes remain the homeowner’s responsibility, and those repairs can be costly.

“Once you start digging up old clay pipes that haven’t seen the light of day for over 50 years, the cost just explodes,” said Heyn