It is great to have your children and their friends splash about in your pool. But as a homeowner, you have a responsibility to make sure anyone around your pool is safe. If you are allowing children to use the pool consider inviting their parents to supervise. Limit the number of children and make sure they are supervised by at least one adult who can swim. You should not allow children or adults to engage in risky behaviour in and around the pool. For example, running around the pool or shoving each other into the pool.
Warning people that they use it 'at their own risk' is not a sufficient legal defence.
If you own a pool or are considering installing a pool on your property, check whether it is covered by your home insurance. If you do not tell your insurance company about the pool, they may refuse liability coverage for pool-related damage or injuries. If you have appropriate insurance coverage, if someone is injured using your pool and sues you, your insurance policy should protect you.
While you may be protected by insurance, you still have a duty to reduce the risk of injury happening. If you do not maintain your property and you are sued it may result in a larger award of damages, your insurance premiums may rise, or it may become difficult to get insurance at all.
If your apartment building has a pool you should check the landlord's insurance and whether there are restrictions in your lease stopping you from inviting your friends to use it.
You can get more information about insurance from the Insurance Bureau of Canada.
If people come to your property without permission and use your pool you may still be liable if they are injured. The fact they broke in and used your pool without your permission would be just one factor that the court would look at in determining liability and in awarding damages. You may also have a right to sue them for trespass and for any damages sustained to your property. Even if you do not sue, your insurance company may sue the trespassers in your name to recover losses.
You should also check with your municipality to make sure you are complying with any local pool by-laws, such as requirements that you have a fence, building or other structure to prevent unauthorized access to the pool.
Click here to learn more about legal issues related to hosting a party at your home.