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What Is The Best Water For Plants? Find Out The Answer Here!

What Is The Best Water For Plants? Find Out The Answer Here!

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Have you ever wondered why we don’t drink rainwater, but it’s good for plants? Or how sometimes tap water can be harmful to plants, but when we drink it, it‘s perfectly fine?

It’s because a different type of water affects different organisms in various ways.

Some say distilled water is best for your plants, and others might even spend a lot of money buying bottled water for their houseplants.

Nonetheless, it is important that all gardeners are familiar with the elements of water so they can decide what kind of water is the best water for plants!

What Is The Best Water For Plants?

Water is filled with lots of minerals and salts that can be extremely beneficial to our health, but somewhat harmful to plants. For instance, excess salts can build up in the soil and prevent proper airflow and nutrient uptake.

Therefore, we should get familiar with the content of water and learn how each substance affects our plant’s overall health.

Let’s dive right in!

Hard Water vs Soft Water

It may seem like every type of water is the same, (I mean, they are all see-through, right?) however, the concentration of certain minerals can actually determine the “hardness” of the water, which is the only difference between hard and softened water.

The calcium and magnesium content of water is the main distinguishing factor between them. Water becomes “harder” when it contains more of these minerals.

Reduced mineral concentrations in the water are how water softening systems function. Soft water often has higher sodium concentrations than higher calcium and magnesium concentrations.

If you live in an area with hard water, you might be dealing with some issues if you are using it to frequently water plants. For instance, calcium is crucial for both plants and humans.

Plants absorb calcium through their roots, and it is involved in numerous biological processes — the cytosolic Ca2+ concentration is an essential intracellular messenger that coordinates responses to a variety of developmental cues and environmental challenges. Calcium is also necessary for various structural roles in the cell wall and membranes, and serves as a counter-cation for inorganic and organic anions in the vacuole.

However, constantly using water rich in calcium, magnesium, and other types of minerals can lead to mineral content build up in the soil, which alters the pH levels and prevents the uptake of other nutrients that are equally as important.

These might accumulate on the side of the pots and additionally impede water infiltration, which can affect the plant’s health.

So, if you live in an area with hard water I would suggest you use filtered water, distilled water, or even rainwater every now and then. This water will wash the soil and all of the nutrient build up.

How Can You Tell If Water Is Soft Or Hard?

If you are not sure whether you are in an area with hard or soft water, there are a few tricks that can help you determine whether you are dealing with hard or soft water!

Some of the signs of hard water include spots on freshly cleaned cutlery and glasses. Typically, calcium carbonate deposits make these spots. You may also see mineral stains on clothes, which also wear out a lot faster when washed in hard water.

Another indicator that you have hard water is low pressure in your home — mineral buildup in the pipes can result in a reduction in the interior diameter and a decrease in water flow.

With soft water, there are no stains on your glasses, your clothes are soft and clean, and the pressure is good!


We know that oxygen is a by-product of photosynthesis and that plants are the main manufacturers of the oxygen we need to live. However, they also need oxygen, which is why we sometimes aerate our lawns and buy porous potting soil that allows air to reach to the plant’s roots.

There is another way that your plant can get oxygen – water!

Water actually has some oxygen dissolved in it, up to 10 molecules of oxygen per million of water. The more of these molecules in the water you are using for your plants, the more vibrant their growth will be!

The amount of oxygen (O2) dissolved in water is simply known as dissolved oxygen. It’s one of the best measures of how well the water is able to support life. The temperature and salinity of the water, as well as other chemical and/or biological requirements, have an impact on the amounts of dissolved oxygen. Fresh water can store more dissolved oxygen than salt water, and cold water can hold more dissolved oxygen than warm water.

According to research, most crops have a bigger root mass when their root zones have higher dissolved oxygen levels. A plant that has a larger root mass develops more quickly and healthily.

Better respiration and the ability to selectively absorb more ions in solution, including the essential mineral salts of nitrogen, phosphorus, and potassium, are characteristics of healthy roots with enough oxygen supply. Reduced root permeability to water results in decreased nutrient absorption when there is less oxygen in the water than there is in the plant.

The advantages of oxygen for plant roots and the rhizosphere in general are well known to growers. However, most people aren’t aware of the amount of oxygen in their irrigation water or that there are ways to raise it.

If you are interested in finding out more about the methods that improve oxygen concentration in the water, check out this video:


As we already mentioned, softened water has a higher concentration of sodium ions and salts. Even though soft water might be safer for humans, the same thing cannot be said about plants.

Most tap waters have normal amounts of sodium that are not as harmful, however, the issue begins when folks start to use water softeners. These softeners replace magnesium and calcium from hard water with sodium ions, which is great because there is no build up in the pipes and it is safer to drink.

However, it can easily lead to salt build up in the soil, which can prevent roots from normal water and nutrient absorption. Harmful chemicals and salt build up is also a common issue if you are overfertilizing your plants, so you should be aware of that as well.

I would recommend you don’t use water that has passed through a softener to water your plants – use filtered water instead.


The most frequent chemical used for the disinfection of water sources is chlorine/chloramine, in one form or another. It also removes iron, manganese, and copper from water, limits the growth of algal, bacterial, and other types of slime in treatment plants and pipes, and regulates tastes and odors.

Small amounts of chlorine are perfectly fine, but if you always use tap water for watering houseplants, it can affect the plant’s roots and also kill beneficial microorganisms in the soil.

It is even worse for sensitive indoor plants because chlorine can quickly disrupt plant health, which can be easily spotted by the browning of the leaves‘ tips and wilting.

Luckily, the solution to this issue is quite simple!

All you have to do is let the water sit overnight at room temperature or keep a bowl of water uncovered in bright light for the day to eliminate chlorine. In addition to this, a water filter can also do the trick.


The temperature of the water can also affect the health of your plants, and there are some tropical plants that cannot stand cold water. These include some types of Alocasia (such as Jewel Alocasia), but also Orchids, Ficuses, Calatheas, and so on.

Root shock from ice cold water may result in lasting root damage, leaf drop, and other issues. Aside from this, when you use cold water for your plants they might think that the seasons are changing and enter “winter mode”. In other words, they will stop growing and enter dormancy.

You might not be able to tell that your plant has entered dormancy and continue with plant care that isn’t applicable to the dormant plant. This can easily lead to overwatering, overfertilizing, and a myriad of other issues.

If you want to keep your plants happy and growing, use lukewarm water instead!

Heavy Metals

No, we are not talking about the music genre here, but rather all of the contaminants in the water that could potentially harm your plants.

Metallic substances that are relatively dense in comparison to water are referred to as heavy metals. In their combined or elemental forms, heavy metals like chromium (Cr), cadmium (Cd), mercury (Hg), lead (Pb), nickel (Ni), and thorium (Tl) can be dangerous. Heavy metals are extremely soluble in aquatic environments, so biological organisms can effectively absorb them.

This applies to the marine environment, humans, and plants as well!

Though some levels of heavy metals might not be as toxic to humans, they are certainly deadly to plants.

Your plants can easily absorb these via their roots, and they can travel through the vascular system to any part of the plant. Common toxic effects on plants caused by both required and non-essential heavy metals include low biomass accumulation, chlorosis, restriction of growth and photosynthesis, altered water balance and nutrient assimilation, and senescence, which eventually results in plant death.

Levels of heavy metal in the water are generally regulated and kept low, however, you should still test the water from a well if you are using it for your plants.


Every type of water has small amounts of fluoride content. Unfortunately, fluoride is a toxin that builds up in plant leaves. Accumulation happens gradually over time. Other activities, including photosynthesis, are seriously affected by fluoride.

It will travel through stomata, which are the transpiration stream from the roots, and settle at the leaf margins. This is how I easily spotted that fluoride was damaging my purple spider plant!

The concentration of fluoride varies between different types of water, and you can’t get rid of it like you can with chlorine. However, you can always choose purified water instead!

Different Types Of Water To Make Your Plants Happy

Water is life, which is why you must choose the best option possible for your plants!

Don’t worry, we got you.

Let’s take a look at some different types of water that you can use for your plants.

Tap Water

Of course the first option is going to be tap water! I mean, it‘s basically free and you can get it straight from the faucet in your house!

Tap water is probably the easiest option, and it can be used for watering many houseplants. However, some plants are sensitive to tap water — it doesn’t have to do with the water quality, it’s just that certain types of plants are extremely sensitive to even small amounts of chlorine in the water!

I swear that it took me forever to figure out why my prayer plant was drooping, and I assume that you probably know the answer by now — that’s right, it’s because of the darned chlorine!

Luckily, the solution to this issue is simple. All you have to do is let the water sit for a day and then it is good to go.

Just a friendly reminder that you can safely use tap water with different types of pothos and philodendrons as well, even if you are using it for water propagation!

Rain Water & Melted Snow

Rain water is probably the safest option to give to your plants as it is rich in natural minerals and the type of water that your plant gets in its own natural habitat!

There is no doubt that rain water will boost plant growth and fruit production.

However, you should be on the lookout for acid rain if you live in a highly-populated area or somewhere near a huge industrial zone.

But if you live in an area with clean air you won’t have to worry about acid rain whatsoever. Therefore, I would suggest you grab some buckets and put them in the yard when it’s raining. You can use this type of water for plants that are sensitive to tap water.

Melted snow is also a great option, just make sure that you collect snow that is white and clean — stay away from yellow snow!

Distilled Water

Distilled water is made by boiling regular water. Boiling gets rid of both contaminants and minerals!

Distilled water is basically like dead water that has nothing in it, which means it won’t be good for your plants. Sure, you won’t be exposing your plant to any heavy metals or salts, but it also won’t be getting the minerals necessary for growth and development!

Bear in mind that some contaminants can still be found in distilled water, especially if you took it from some farm runoff. However, these impurities can easily be removed from tap water.

Purified Water

Purified water is similar to distilled water. Instead of boiling, purified water has undergone a treatment known as reverse osmosis, which is why it is often referred to as R/O water.

This technique helps to get rid of bacteria and contaminants, but the water also loses its good substances. In this case, your water is nothing but two hydrogen and one oxygen atom!

Purified water is used when you are having issues with overfertilization — in this case, there is a mineral buildup in the soil that doesn’t benefit from the additional minerals in the water. Therefore, you use purified water that lacks these nutrients to freshen up your plants.

In some cases, this treatment has one more step where the good minerals are added back to the water, however, we avoid using these because it has caused stunted growth in numerous plants.

Aquarium Water

If your fishies love their water, your plants are going to love it too!

Fresh water from the fish tank is not as good as rain water, but it will still do the trick. This water is filled with nutrients and small animal waste that can serve as a fertilizer.

Unfortunately, only small amounts of water can be used from fish tanks, and it isn’t enough to supply all of the plants in your house (well, at least not in mine!). Therefore, it cannot serve as a permanent water source unless you have a large indoor fish tank.

Bottled Mineral Or Spring Water

Using bottled spring water is probably the better option. It is as good as rain water, although rainwater is still the best option!

Mineral water contains minerals and high sodium levels that can easily cause problems for your indoor plants. In addition to this, it is quite pricey, so you will just lose money if you constantly buy mineral water for your plants.

Filtered Water

If you have no other option than to use tap water, the least you can do is use filters to improve the water quality.

Luckily, there are various options available that are cost-effective and effective-effective, which means that they will both successfully filter out all of the contaminants and reduce mineral and salt levels.

You can either get your own filtration tank from amazon or a faucet attachment able to filter the water.

Frequently Asked Questions

1. What type of water helps plants grow fastest?

The type of water that helps plants grow fastest is definitely rain water. The best care tip that anyone could possibly give is to try and mimic the plant’s natural environment, and this includes the type of water.

Rain is the best option for any type of plant because it is filled with natural minerals that are essential for growth and development.

If you live in an area with low rain, then you can use aquarium water because it contains animal waste that can serve as a fertilizer, which also boosts growth!

2. How can I make tap water better for my plants?

The only issue with tap water is that it contains chlorine, and this substance can sometimes be harmful to certain types of plants. The easiest way to make tap water better for your plants is by leaving it to sit for 12 to 24 hours.

This will eliminate the chlorine present in tap water and also preserve all of the good minerals required for maintaining optimal plant health.

You can also install a filtration system if you are dealing with plants that are extremely sensitive to even small traces of contaminants.

3. Are distilled and purified water good for plants?

The answer is yes and no. Yes, because these types of water do not contain harmful contaminants and bacteria that could potentially damage the plants, and no because they also don’t contain healthy minerals and nutrients required for normal growth and development.

Boiling and reverse osmosis get rid of any elements in the water – whether they are beneficial or not, and you are left with just two hydrogen atoms attached to one oxygen!

Sure, you can sometimes use purified water — it is highly recommended if you are dealing with overfertilization but don’t want to repot your plant. However, if you constantly use it your plants won’t get any type of minerals. They won’t stay thirsty per se, but will stay hungry for minerals and nutrients.

4. What types of water should I avoid watering plants with?

Softened water isn’t recommended when watering plants because it contains high amounts of salts that build up in the soil and prevent the normal functioning of the root system.

If you consistently use hard water, which contains a high concentration of minerals such as calcium and magnesium, these can also build up and alter the nutrient content in the soil.

You should also avoid using chlorinated water, especially in delicate plants that are sensitive to any types of contaminants.

To Sum Up

Who would have known there are so many types of water that can be used for watering plants?

I always thought that we could just use tap water — I mean, if it is good for us, then it must be good for the plants as well, right?

Well, it seems that we have all been wrong. But, hey – you live and you learn!

When it comes to taking care of houseplants, even if you are dealing with succulents such as cacti, they still need some high-quality water.

Avoid using chlorinated water filled with contaminants, but also don’t go crazy with the purified water either!

It would be best if you invested in a filtration system so you know that you and your plants are getting the best out of the water.

I hope this article was helpful, until next time!

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