The dirtiest thing at your child's childcare is also the one thing they can't go without.

Coming off the back of one of the worst Australian flu seasons in recent history, keeping kids healthy has never been more important.

For many parents, the day care centres where their kids spend large portions of their days is a big point of concern. Because toddlers, snotty noses, mud and a lack of toilet training = sick kids, right?

According to COMSAN childcare sanitation expert, Danielle Sheridan, even shiny, new childcare centres can be full of harmful contaminants you’d rather your child not be exposed to.

“We measure the levels of contaminants on different areas within the centres and the majority of the results that come back are actually on par with that of an abattoir. It’s pretty shocking,” she told Mamamia.

“You’d be surprised how grubby some centres are. These contaminants can remain on surfaces for several months, and it just takes one area that someone hasn’t been stringent in cleaning, whether it be a toy or a surface, and just one child for it to spread like wild fire.

“If parents could see how dirty the centres were, they wouldn’t drop their kids off.”

When it comes to the danger zones where kids are most likely to be exposed to bacteria, Sheridan explained it’s a double edged sword: the dirtiest thing is also the one thing they legally can’t go without.

“Every time I go into my daughter’s daycare, she’s got her mouth around someone else’s water bottle, that’s by far the biggest breading ground.”

“But this is really hard for staff to monitor because by law, water has to be readily available to the children at all times. And the kids are too young to understand that they can’t put someone else’s water bottle in their mouths.

“You can have a great centre and be doing all the right things, but a child’s a child.”

Sheridan also warned soft climbing blocks, and toys are among the equipment that yield the highest results of contaminants.

But before you jump in the car to collect your bubs from childcare for a life in isolation, it's not all bad news. From Sheridan's experience, there are things parents can do to give kids the best possible chance of being healthy and happy in childcare.

First, ask questions.

"The most important thing to do is ask questions. What measures does the centre take in terms of cleanliness and hygiene? How regularly do the cleaners come? What's the staff protocol with cleaning play equipment and how often are the toys washed?"

"Having policies displayed is a good sign, because looking clean isn't really good enough anymore with kids getting sick all the time. Ask if they have a sanitation certificate, or if they'd be open to having their centre tested by a company like COMSAN."

Another good tip is to be aware that how you see a childcare centre during 'walk throughs' aren't always a realistic example of how the centre looks on a day-to-day basis.

"Of course the bins are going to be empty and the benches wiped [during walk throughs], so it's hard to gage how sanitised the centre is just by looking - you need to ask the right questions."

"And take a closer look. Is hand sanitiser everywhere? Have a look at the kids, if there are a handful of kids there with bright green snot, it's not a great sign."

LISTEN: Mamamia talks all things childcare on Hello Bump (post continues after audio...)

Above all else, Sheridan stressed the most effective thing parents can do to make sure their kids don't become unwell at childcare is to respect the centre's exclusion policy. In other words - don't drop a sick child off at childcare.

"It's a tough call, I've had to make that call as a parent. It's hard because parents need to get to work and they might not have an option, but it's so important to be aware that keeping your children home when they're sick is for the benefit for everybody, no one wants sick children."

"At the end of the day, it's not OK to bring your kids into the centre sick because it puts everyone at risk."

For more information on COMSAN and their services, visit their website.