Now you have a better grasp on what type of water to use on house plants and how harmful some types of water can be. The best way to make sure your plants are getting a proper amount of plant-friendly water is to check the moisture content in your soil regularly with a moisture meter and monitor plant growth. If you notice that the plant's growth is stunted or the leaves are turning yellow, it's a good sign that you need to examine the type of water you're using and the frequency of watering and switch up your routine.