If you are specifically worried about water damage you should shop with The Co-operators. They offer the most comprehensive water coverage in the insurance industry. Other companies offer comprehensive water as well but there are a lot more restrictions with the product.
You want enough coverage to replace your physical contents that you own in the property. Normally in a rental that is your appliances and betterment and improvements are normally covered. Upgraded floors etc. The liability of 1/2 million is what you want to make sure of as well.
Here is a link to the info for water coverage. The point of insurance is peace of mind that you will be put back to the same place you were prior to a loss. If you are worried about your current insurance coverage you more than likely don’t have the right coverage in place. Price is important but make sure you are looking at any exclusions and coverage limits.
https://water.cooperators.ca/
Good luck! Hope any of this is helpful