Thousands of water meters installed in homes across Minneapolis are getting a 21st century upgrade after years of rushing water has gradually taken a toll on them.

The city is replacing nearly 100,000 water meters over the next several years, swapping the aging devices with new ones that will allow for real-time readings. It is about 15% of the way through the home replacements.

Since the 1990s, the city has read meters once a month by driving a van equipped with a special radio device up and down the alleyways. The new meters will feed readings every six hours to Wi-Fi-enabled collectors on traffic poles and other infrastructure. Several metro area suburbs already use similar technology.

Water meter readers once went door-to-door across Minneapolis — sometimes equipped with home keys — visiting basements to read the meter in person. That changed in the early 1990s when the city switched to meters that periodically dialed in readings using the telephone.

The new meters will allow residents to check their usage in real time and be alerted to potential leaks. Glen Gerads, the city's director of water treatment and distribution, said leaks are often caused by toilets that are continuously running because of a broken valve.

"You will be able to sign up for leak alerts that would tell you that, 'We don't know for sure, but it looks like you might have a leak in your toilet. Here are some things you should maybe look at,' " Gerads said. That system won't be in place until the upgrades are further along.

About 92,000 of the nearly 100,000 replacements are in residential properties. The city is working through the Corcoran, Erickson and Standish neighborhoods of south Minneapolis and will soon be moving to the Northrop, Hale and Diamond Lake neighborhoods.

Gerads said the biggest challenge is arranging the appointments with homeowners, who receive letters about the project and must schedule an appointment.

"Everybody's got a busy schedule," Gerads said. "Nobody wants to take off time from work. So getting people to make this a priority is a bit of a challenge."

People may notice a change in their monthly water bill, since the current meters are about 25 years old, and deteriorating rotating mechanisms decrease their accuracy.

"As water meters age, because they're mechanical, they underregister and don't overregister," Gerads said. "At the end of the day, it should not be a significant increase."

High-tech water meters worry some people, however. Some have expressed privacy concerns about the real-time readings, as well as about the health effects of electromagnetic frequencies. About 200 people opted out several years ago when St. Paul upgraded from touch-pad readers to radio signal devices, for example. One man registered the websites and to highlight criticisms of the new technology. The latter website is now controlled by the city.

Gerads said people can opt out of the Minneapolis upgrade but will pay an extra charge for touch-pad readings.

"We've had a handful, I think. Not many," Gerads said.