As floodwaters in Nova Scotia recede and people return to their homes to assess the damage from this weekend's historic rainfall, they might be wondering how to check their well water for contamination.

Elizabeth Kennedy, director of water programs with Nova Scotia's Department of Environment, said after a flood, wells may become contaminated with bacteria or chemicals that could make you sick.

She said wells may become contaminated if your home was evacuated and the power was out for an extended period, making the water stagnant.

"These conditions can allow bacteria or chemicals to concentrate in their well or in their plumbing system," Kennedy told CBC Radio's Mainstreet on Monday.

But the biggest concern, she said, is harmful bacteria like E. coli in sewage.

"Well heads [that] come out of the ground, those areas can get flooded, and that water might be the same water that's flooding septic systems nearby," Kennedy said.

"Wells are designed to keep out surface water from getting into the well, but they're not always perfect, and so that's a risk."

Chemical contaminants in well water are less likely, she said, unless there was a spill.

Still, Kennedy said, it's important for homeowners to check for bacteria.

"If they're returning and they know or suspect that that area around their well had been flooded — even if it didn't come all the way up to the top of the well that was sticking out — then they should definitely not drink that water," she said.

She said the water also shouldn't be used for cooking or bathing, unless it's boiled and cooled first.

Kennedy said if you suspect your water has been contaminated, you should first flush and disinfect your well.

Flushing involves running your taps until the water is clear. A step-by-step guide on flushing and disinfecting your well with bleach can be found here.

Once you have flushed and disinfected your well water, you can have it tested by purchasing a testing kit at Nova Scotia Health Authority locations. They cost about $30 to $50.

Kennedy said you can ask the lab for a presence/absence test that will check for total coliform and E. coli bacteria.

Test kits were provided to homeowners following the wildfires in the Halifax and Shelburne areas of the province, but it's unclear if that will happen after the floods.

In an e-mail to CBC News, a spokesperson for the province said it paid for well water testing for wildfire evacuees because "they were displaced for a long period of time, which significantly increased the chance for bacteria to develop in their well and for chemicals to concentrate.

"Additionally, with about 15,000 homes requiring testing, the province needed to step in and arrange for testing to be available at private labs that could manage the capacity."

More information about testing your well water can be found here.

A notice from the Halifax Regional Municipality on Tuesday said water from the Halifax Water system is safe.