KITCHENER -- More people are seeking out COVID-19 tests as cases continue to rise in Waterloo Region and the province.

Anyone arriving at the testing sites should expect long lines and some are even being directed to come later. There are concerns about what could happen if the demand for testing continues to increase in the coming weeks.

Staff at the Grand River Hospital's drive-thru testing site said people were lining up as early as 4:30 a.m., even though it doesn't open until 7:30 a.m.

Since school began earlier this month, the testing site's capacity has nearly doubled.

"We were seeing anywhere from 350 to 400 a day, we are now consistently seeing over 600 patients per day," said Sarah Sullivan the testing centre's operations manager.

On Sept. 15, the site completed 645 tests -- the most it's ever performed in a single day.

St. Mary's General Hospital is seeing a similar spike in testing demand.

"Pretty much since school has started we have been testing over 100 people per day and it has gradually gone up," said Stephanie Pearsall, the COVID testing lead with St. Mary's General Hospital. "(It) goes up every single day, so yesterday was our highest volume, like I'd say at 170."

The province also broke a single-day testing record on Saturday, completing more than 40,000 tests.

The lines are long enough that people are being turned away and told to come back later.

Minister of Health Christine Elliott said there are no plans to shift back to priority testing groups.

"We want everyone who is concerned to get a test," she said.

Officials ask anyone who's booked an appointment to keep it.

"For sites that are booked appointment only, if there are people that are not showing up, it doesn't allow them to maximize the use of all the available appointments," Pearsall said.

Pearsall also said it can take longer now that more children are being tested.

"Children tend to be anxious and we are doing our best to give them the information they need so that they're less hesitant when we perform the test," she said.

Higher testing capacity is expected soon, but for now, anyone going to a testing site should be ready for a long haul.

"You can bring some activities for your children, food and water to keep yourselves comfortable while you're waiting, but also be as patient as possible," Sullivan said. "Our staff are working as diligently and hard as they possibly can to get everybody through."

The province is promising more details on expanded testing capacity this week.

Premier Doug Ford suggested it could include testing at pharmacies, more pop-up assessment centres and extended hours.