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Does Rainwater Help Indoor Plants? (Watering Guide)


Do something for your planet Earth and for your wallet! Water is a precious resource. Collect rainwater in a water collector and use it to water your vegetable garden and ornamental plants.


Does rainwater help indoor plants grow?

The chemical composition of tap water affects the health of the plant. Indeed, chlorine, a disinfectant, and fluoride, a chemical component that prevents cavities, are present in our tap water. Moreover, tap water is also characterized as “harder” than rainwater, i.e. it has a high calcium and magnesium content. In order to make it softer, sodium is added to soften it.


Houseplants are sensitive to these four chemical elements, which are not present in rainwater. In fact, if the leaves of your houseplants develop stains, discolorations or are burned, it may be due to the toxicity of fluoride and chlorine. If you see white deposits on the leaves, it is probably due to calcium and magnesium. Sodium attacks the plant cells.


In short, you will have understood that using rainwater to water your indoor plants will only be beneficial for their health and development. Moreover, rainwater does not have the toxic compositions presented above and it offers another advantage: it contains oxygen, an essential element against the asphyxiation of the roots of your indoor plants. We therefore recommend watering with rainwater for the well-being of your indoor plants and the environment.


Why collect rainwater?

45% of the rainwater we use does not need to be potable. Recovered rainwater is soft. This ecological gesture allows us to reduce consumption. And also to make savings! Indeed, a gardener with a cultivated surface of 200 m² and using only rainwater for watering, will save nearly 200€ per year.


The water collector can recover up to 80 to 90% of the water that falls on the roof. In case of a heavy storm, it can also act as a water retainer to limit flooding.


How to collect rainwater to water your plants?

When you have a garden or a balcony

Outside, you can install a tank to collect rainwater. Connected to the gutters of your house and equipped with a filter, you can find different sizes ranging from 100 to 500 liters. This kind of tank is sufficient for watering plants and washing cars/bikes.


Also, in apartments, if you have a balcony and if you are a bit of a handyman, you can also use this principle of the tank presented above but in a small size. However, beware of the weight that rainwater harvesting could involve if you have a suspended balcony.


The norm concerning the weight on a terrace is 350kg/m2. After this verification, you could choose a container of an adequate size for your needs. The method is the same as for outdoor use. Then, you have to connect your container to the gutter. This is often vertical and usually has a removable joint. If this is the case, simply dismantle it and install a PVC elbow with the right diameter. And above all, don’t forget to ask your landlord’s permission, if you are a tenant.


On the other hand, for the less handy among you, you can use rain chains which are aesthetic and very ingenious.

Be careful though: when your container is full, it is important to be able to redirect the rainwater to avoid water damage.


When you don’t have an exterior

If you’re not lucky enough to have a balcony, here’s another rainwater harvesting tip: install a planter on your windowsill. Drill a hole in the window and connect a simple hose to a watering can, for example. The rainwater will be directly accessible in your watering can, ready to use.

So, now that you know the benefits of watering your plants with rainwater, you would be wrong to deprive yourself of it.


How to water your plants with rainwater

Having a green thumb is good, but watering your plants with the right technique is even better. It should be noted that the watering system is declined in 2: by the top and by the bottom


Watering from above

For this, the possession of a watering can (or a bottle is enough for indoor plants) is essential. For this method, you only have to water the substrate. The water seeps into the soil and then into the roots from where it will flow into the saucer. In most cases, the water tends to stagnate in the saucer which can cause the roots to rot. So you have to be careful with it. Wait a few moments and empty it if necessary to avoid any excess of humidity. After 30 minutes remember to check the saucer.


Watering from below

Watering is done on the surface by soaking or drenching. This technique is recommended for carnivorous plants or plants with waxy foliage (plants that do not like to have wet leaves and flowers). This method is also adapted to plants installed in suspension like the orchid. To do this, simply immerse the pot or planter in a sink or bucket of water. Remove the plant once the surface is wet.



Water is a precious element that is becoming increasingly rare on our planet. Human consumption of water is constantly increasing, while the available resources remain the same, and are even in danger of deteriorating. It is therefore essential to preserve fresh water, synonymous with life, which represents only 3% of the total water reserves available on earth.


We explain how and why to use rainwater for your indoor (and outdoor) plants.

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