In most cases, tap water is perfectly fine for watering your houseplants. However, there are a few things to keep in mind: - If your tap water is heavily chlorinated, let it sit out for 24 hours before watering to allow the chlorine to evaporate. - If you have a water softener, the added salts can build up in the soil over time and harm your plants. Consider using rainwater or filtered water instead. - Some plants, like carnivorous plants and certain orchids, are more sensitive to the minerals in tap water. For these picky plants, it's best to use distilled or rainwater. If you're unsure about the quality of your tap water, you can always have it tested or opt for a safer alternative like filtered or rainwater.