Calgarians are being asked to have shorter showers, run dishwashers and laundry machines only when full, and flush toilets less, after the second catastrophic failure of an essential water main caused a dangerous shortage of the city’s water reserves. Nearly 80 million litres of water were lost after the Bearspaw South Feeder Main ruptured without warning on Tuesday evening, trapping more than a dozen travellers in their vehicles in the icy current, and leaving city officials rushing to identify the cause and repair the damage.