Could Tap Water Be Harming Your Indoor Plants?

by Francesca Macias / Mar 14, 2023
Could Tap Water Be Harming Your Indoor Plants?

What do you use to water your houseplants? Have you ever wondered if tap water is good for them? Or if distilled water is even better? How about rainwater or filtered water?

Read on to discover how (and why) the water you use can affect your plants, for better and for worse. 

And find out the absolute best water source for healthy indoor plants like succulents, peace lilies, cacti, orchids, calathea, pothos, ficus, snake plants, and other popular houseplants. 


The Problem With Tap Water (That Nobody Talks About)

It’s easy and convenient to use, but what if your tap water is actually killing your plants? 

You see, tap water in all 50 states contains all kinds of chemicals, heavy metals, and toxins that aren’t just dangerous to you. They’re dangerous to your plants, too!

Specific contaminants can cause visible damage, root damage, or soil damage to plants. And chlorine, for example, can cause all three. 

Which means regularly watering your plants with contaminated tap water can lead to browning, yellowing, and wilting, while secretly attacking roots and soil in invisible ways that can contribute to disease and death over time.

Let’s take a look at the most common contaminants lurking in tap water that have been shown to be detrimental to indoor plants.


Introducing The “Big Three”... 3 Common Tap Water Contaminants Known To Harm Indoor Plants

  • Chlorine kills.
  • Chlorine is added to tap water to kill bacteria and microorganisms. So think of water like food for a second. Food can have “good” bacteria like probiotics, and “bad” bacteria like Salmonella. 

    The same goes for water. But the problem is, chlorine kills “good” bacteria (and microorganisms) plants pull from water and soil to survive, which can then cause lasting damage from roots on up. Plus, chlorine can easily dry out plants’ leaves, which can quickly lead to unexplained yellowing, browning, and wilting. 

  • Fluoride can cause leaf burn.
  • Like chlorine, fluoride is almost always added to tap water to help prevent tooth decay. But high levels of fluoride in water can cause leaf burn in plants. And leaf burn leads to yellowing, browning or curling of edges of the leaves, as well as a general wilting or drooping of the plant. 

    You see, plants and humans alike only need tiny, potentially “trace” levels of fluoride to get its benefits. Anything more than that can lead to serious problems. The severity of the effects on your plants depend on the level of fluoride in your water, as well as the species of plant. 

  • Lead can cause chlorosis, necrosis, and more.
  • It’s no secret that lead is toxic to humans, but it's also toxic to plants. Watering houseplants with lead-tainted water can lead to chlorosis (which turns leaves yellow and keeps veins green), necrosis (which leads to black or brown spots on leaves or stems), and even stunted growth.

    And as you’ll see in just a second, lead isn’t the only heavy metal found in tap water that can do lasting damage to plants. It’s just the most common!


    Additional Tap Water Contaminants That Secretly Attack Your Plants

    For reference, more than 300 contaminants have been found in tap water supplies in the U.S. (Scary, eh?) Which means chlorine, fluoride, and lead aren’t the only contaminants that can be detrimental to your houseplants. 

    Here are just a few more specific contaminants to avoid: 

  • Pesticides. Turns out pesticides can kill insects and plants. Especially if they’re over-applied or applied at the wrong time. You could unknowingly apply pesticides to your plants every time you water them with tap water.
  • PFAS. These man-made chemicals are nicknamed “forever chemicals” for a reason. Instead of breaking down over time, they accumulate over time. Which means they can build up in soil and cause new and permanent stress to plants. 
  • Chromium-6, copper, and zinc. Like lead, these other heavy metals can accumulate in soil, then damage plant roots and cells. And any damage to roots can make plants susceptible to root rot. 
  • Pesticides, pharmaceuticals, microplastics, and more! As you see, the list goes on. The thing to remember is the effect tap water contaminants have on houseplants varies depending on the type of plant and the level of the contaminant. 

    If I Shouldn’t Use Tap Water, Then What Should I Use?

    As you can see, chlorine-free, fluoride-free, and lead-free water is almost always best for houseplants. But for all the things that should be removed from water, there are a few things most plants would like to stay!

    You see, minerals typically found in tap water, like calcium, magnesium, and potassium, are actually good for most plants.

    Calcium, for example, is important for the formation of cell walls and helps to strengthen the plant's structure. It also plays a role in the transport of water and nutrients throughout the plant. 

    Magnesium is a key component of chlorophyll, the pigment that gives leaves their green color. It is also involved in the process of photosynthesis, which is how plants convert light into energy.

    And potassium plays a role in the regulation of water balance and stomatal opening, which is also important for photosynthesis. 

    So plants need a certain level of minerals to thrive. And as you’ll see in just a second, most alternatives to tap water, unfortunately, don’t have them!


    What About Distilled Water?

    Distilled water can be good for plants, in moderation. You see, distilled water has everything removed from it. Which sounds ideal, but poses a problem.

    Yes, all of those chemicals and contaminants are gone. But so are those beneficial minerals that most plants need.

    The bottom line is, distilled water takes away the bad and the good. Which means it can be fine for your plants from time to time. But for most species, a diet of only distilled water is not ideal.


    Reverse Osmosis Water Has The Same Problem As Distilled Water—No Minerals!

    Reverse osmosis water isn’t all that different from distilled water. While it is probably cleaner, it still has the same issue: It has been completely stripped of beneficial minerals.

    That’s why most plants can’t thrive on a diet of reverse osmosis water only. 


    What About Rainwater?

    Rainwater, is for the most part, a fine alternative to tap water. It’s typically free of chlorine and other chemicals. However, it can be too acidic for certain species.

    Acid-loving plants such as azaleas and camellias tend to thrive in rainwater. But other species that prefer more alkaline water, such as African violets, hibiscus, begonias, and impatiens may struggle to absorb the nutrients they need from acidic rainwater. 

    And we haven’t even mentioned the biggest challenge with rainwater yet; the inconvenience. I.e. Collecting it!

    Not only do you need to collect it, you probably should measure the pH in it before feeding it to your plants to ensure it’s safe for your species.


    Why The Right Filtered Water Could Be Best For Your Plants

    You can still use tap water to water your plants. It just needs to be clean! 

    If you can minimize chlorine, fluoride, and lead in your tap water, you’re on the right track. And if you can do that without targeting potassium, calcium, and magnesium, even better. 

    But the vast majority of mainstream water filters do NOT target fluoride. And the few that do, like Reverse Osmosis filters, remove the important beneficial minerals we just mentioned. 

    ALL Clearly Filtered water filters minimize chlorine, lead, and fluoride, WITHOUT targeting beneficial minerals like calcium, magnesium, and potassium. 

    So unless you already have hard water with excess minerals, or a unique species with unique needs, Clearly Filtered filtered water may be the absolute best choice for your houseplants!


    Additional Considerations When It’s Time To Water Plants

  • Beware of hard water. 
  • While minerals like calcium, magnesium, and potassium are beneficial to plants, they can also be harmful in high concentrations.

    Remember, hard water is caused by a build-up of excess minerals, like calcium. Those excess minerals often leave white deposits on surfaces like sinks and faucets, and soap scum in the shower. Plus, hard water can even have a metallic taste and a cloudy look. 

    The critical problem with hard water is it makes it difficult for plants to absorb nutrients due to mineral build-up in soil. So if your water is hard, you may need to soften it before filtering it. 

  • pH levels matter to certain species.
  • It's also important to consider the pH of the water, as different plants have different preferences. 

    pH is measured on a scale of 0 to 14, with 0 being the most acidic and 14 being the most alkaline. Water can be tested for pH using a pH test strip or a pH meter. As a general rule of thumb, most houseplants will grow well in water with a pH between 6.0 and 7.0.

    Clearly Filtered filters tend to have a minimal effect on pH.

  • Moisture level: Overwatering and underwatering can cause root rot.
  • It doesn’t matter what source of water you use, too much water, or excess water, can cause poor drainage of the soil which can lead to root rot. You see, when the roots of a plant are constantly submerged in water, the oxygen supply to the roots is reduced, causing the roots to suffocate and eventually die. 

    And too little water, or less water, can cause root rot, too. Because underwatering leads to fungi growth from dry soil. 

    So when it comes to plant care, water source matters… as does how often you water your plants and the amount of water you use! 


    How Often Should You Water Indoor Plants?

    The frequency of watering indoor plants depends on the specific watering needs of each type of plant. But generally, most houseplants should be watered when the top inch of soil is dry. And they should be watered for moist soil, not soggy soil. This is why drainage holes, potting and repotting, potting mix, potting soil, growing season, and even room temperature matter, too!

    The best thing you can do is to be aware of specific plant needs for every type of plant you have. And honor those needs! 


    Upgrade To Clearly Filtered To Keep Your Houseplants Happy & Healthy

    Our advanced water filters minimize hundreds of contaminants (including chlorine, fluoride, lead), without targeting minerals (like calcium, magnesium, and potassium).

    That’s why most of our plant-loving friends like the ease and convenience of our breakthrough filtered water pitcher (which you can treat like a watering can!), while others with lots of plants to water prefer our under-the-sink system to get filtered water from any faucet! 

    If you want to keep your houseplants happy and healthy, keep them away from chlorine, fluoride, lead, and other common tap water contaminants!