TORONTO -- An extensive, year-long study on lead content in municipal drinking water found that roughly one-third of water samples tested across Canada exceed the acceptable levels set by Health Canada.

The Toronto Star, one of the media organizations involved in the investigation, has an extensive guide on how to find out if your tap water is contaminated with lead -- and what to do next.

Here are some more answers about lead contamination in drinking water and what you can do.

How does lead get into our drinking water?

According to Health Canada, lead is not typically found in natural water sources or treatment plans in Canada. In most cases, lead seeps into the municipal water supply through aging infrastructure. Lead pipes, old wells, plumbing parts, even fittings, soldering, faucets and valves can all leach into drinking water. The water’s acidity or alkalinity, temperature, types and amounts of minerals in it, and how long it’s been standing in the pipes are all possible factors that can affect the amount of lead it contains.

What are the health implications of drinking water that is contaminated with lead?

According to the U.S. Centers for Disease Control and Prevention, lead is absorbed and stored in our bones, blood, and tissues, and is a “source of continual internal exposure”.

Lead is a neurotoxin and exposure to the metal from drinking water can result in high blood pressure, heart and kidney disease in adults, and neurological and behavioural problems, and lower intelligence in children.

“It definitely impacts children more. Their bodies absorb lead at a higher rate than adults,” Declan Keogh, one of the student journalists from Ryerson University who was involved with the year-long investigation, told CTV’s Your Morning.

“Up until fairly recently, people didn’t think that small amounts of lead impacted people - like the 5 parts per billion number that’s set by Health Canada. But now they’re seeing that it does give you things like heart diseases, it impacts pregnancies, and unborn fetuses.”

The CDC says “no safe blood level has been identified for young children” and “all sources of lead exposure for children should be controlled or eliminated.'' Children typically show signs of overexposure at lower levels. Lead can also be passed through breast milk.

Showering and bathing, however, is considered safe even when the lead amount exceeds guidelines, since human skin does not absorb lead found in water.

How do I know if my tap water is safe or not?

“That’s really the problem here, is that there hasn’t been enough support from municipalities to help homeowners,” said Lyndsay Armstrong, a Nova Scotia-based student journalist on the investigative team.

“During this investigation, we found that really, people had high lead in their water and just had no idea. They had no idea it was a problem, they had no idea they needed to test for it. In a lot of places, lead isn’t even considered one of the base level compounds that you can test for in water.”

In Canada, lead was a commonly used material for water pipes until 1975, when the metal was banned under a revised National Plumbing Code of Canada. Older homes may still contain lead materials, however.

Health Canada advises homeowners to check with their municipality, water utility provider, or plumber to find out whether there are lead service lines in their neighbourhood.

Homeowners and residents can also check the water line that comes into the home (which can sometimes be seen in the basement, near the water meter). If it is greyish-black, easily dented when scraped with a sharp object, it could contain lead.

How do I test my own water?

There is no national standard for doing so easily, with the process different from municipality to municipality, said Armstrong.

See if your municipality has a water sampling program or test your water upon request. Contact your local public health authority for assistance. You can check your city’s website to figure out the nearest place to get a water test. Some municipalities offer free tests, while other places do not. If you are a well-water drinker, you are responsible, Armstrong added.

“If you’re not able to easily find the best way to get your lead tested, you should speak to your city councilors, your MP, and make it known that this is important to you and that you’re worried about your water.”

There’s lead in my drinking water. What can I do?

The most effective way, but also the most expensive, is to replace the lead water pipes inside your home and the service lines leading to your home. In most cases, homeowners are responsible for service lines up to the curb only. With costs ranging from $5,000 to $10,000, this option is expensive and unrealistic for some people.

Another option is to “flush” your water: run your faucets for up to five minutes before you use it in the morning or when you get home from work, for example. Flushing your toilet, taking a shower, or doing a load of laundry are other ways to clear your pipes of water that has been stagnant for several hours.

There are pitcher water filters (carbon-based) and water filtration treatment systems (distillation and reverse osmosis), that you can use or install that can also help significantly reduce the lead content in your water. Make sure they meet standards by ensuring the product is certified by NSF International. Filters need to be installed correctly and maintained regularly in order to be effective. Installing them at the tap most commonly used for drinking is recommended to maximize effectiveness.

Unlike bacterial contamination, boiling your water will not help reduce lead content, and in fact would increase the amount, as it concentrates the lead.

Other steps you can take to reduce your exposure include:

• Avoid hot tap water when using it for consumption, as the higher temperature releases more lead and other metals from your pipes

• Use cold tap water for drinking, cooking, preparing baby formula, etc.