Calgary city council held a special meeting Monday to talk about $3.5 billion in improvements needed for the city's water and sewage systems.

​Staff outlined a 10-year plan Monday for upgrades and new infrastructure for the water, sewage and stormwater programs.

Utility Increases in 2014

Water: Flat rate monthly: $72.57, up $4.99 (7.4 per cent hike). Metered, average monthly household charge: $48.38, up $3.33 (7.4 per cent hike).

Wastewater: Flat rate monthly: $52.93, up $6.30 (13.5 per cent hike). Metered rate, average monthly household charge: $35.32, up $4.20 (13.5 per cent hike).

Drainage: Stormwater monthly charge: $9.20, up from current $8.77.

The proposal works out to $350 million every year for the next decade — nearly double what the city budgets annually for ongoing utility work.    

The biggest item is a major expansion of the Bonnybrook Wastewater Treatment Plan, which handles more than half of the city's wastewater.

"As the city grows, we are going to have to spend hundreds of millions of dollars ensuring the water that comes out of your tap is clean and the water you flush down the toilet is cleaned. And we have to figure out how to pay for that. Ultimately it all comes down to the… taxpayer," said Mayor Naheed Nenshi.

Coun. Gian-Carla Carra says the city has to keep up with these expenses, so it's the cost of having a city the size of Calgary and one that is expected to keep growing.

The upgrades will likely be passed on to residents.

Council approved double-digit utility increases this year, but also looked at how much more those bills will have to go up in coming years to pay for the improvements.

A decision on the matter is expected to be made in May.