You may have heard that some plants don’t like tap water and that it can even kill them – which is a bit of a problem for anyone who has a lot of houseplants and wants to water them easily, cheaply, and efficiently.
It can be expensive to buy water specifically for your plants, and that might lead you to wonder “is boiled tap water good for plants?”
Cold pre-boiled tap water is a good for plants because it’s an effective method to reduce the calcium that is present in the water. Calcium is one of the things that affects sensitive plants, because it clogs up their roots and makes it hard for them to draw in water and nutrients.
The water must always be cold before you use it!
There are a few things in tap water that your plants may not like, the most notable ones being chlorine and limescale (chalk dissolved in the water).
You are more likely to have to worry about limescale if you live in an area with very hard water.
If you are curious how hard the water is in your state you can check it out here.
It is easy to get rid of the chlorine in tap water until it’s plant safe; you simply need to leave a container of water sitting on the side, and it will evaporate off. You should do this for at least 24 hours before using the water for plants, and for longer if you have a large container.
Tip: Greater surface area will allow for faster evaporation.
You can also use a water filter to get rid of the chlorine and any other unwanted contaminants, but this is unnecessary and can be expensive.
You may have a water softener, which is a good way to deal with the limescale, but not if you want to water your plants with tap water.
To soften the water, sodium carbonate is added, and most plants cannot handle this, especially in large quantities.
It’s not a good idea to use softened water for houseplants.
Is It Good To Water Plants With Boiled Water?
Boiling tap water is a good way to kill off any contaminants you might be worried about, although as tap water is safe for human consumption, there shouldn’t really be anything in it that will harm your plants.
The best reason for boiling tap water for plants is that it will help to separate out some of the limescale that otherwise is dissolved throughout the water.
It’s a good way to neutralize limescale because other methods, such as softening the water, are not generally suitable for your plant. For example, using vinegar or sodium carbonate will quickly kill most plants because they can’t tolerate the addition to the soil.
However, remember that boiling water is quite energy intensive and is not a great way to deal with water hardness overall – it takes time and power, and if you have a lot of plants to water, it could prove quite inefficient.
You will also have to make sure that the water is completely cool before using it to water your plants.
Boiling water is a great way to kill plants, and even warm water may upset some more sensitive specimens.
Others (particularly tropical plants such as orchids) may prefer warm water, but will be fine with room temperature.
Allow the water to cool for an hour or so after boiling, and then use it to water your plants for a less limescale-y version of tap water. If possible, you should also allow the chlorine to evaporate off as well by using the technique stated above.
If you can instead use rainwater, you will find this an easier solution that’s less expensive and more eco-friendly, and your plants may be happier for it. You may be able to collect rainwater by simply putting a dish or bowl outside and letting it fill when it rains.
If rainwater this isn’t viable in your situation, cooled boiled water is probably the next best thing.
How Long Should You Boil Water For Plants?
You will probably find that boiling it just once in the kettle is sufficient, so a few minutes (depending on how full the kettle is) should do.
The limescale should cling to the hot surface (the bottom and sides of the kettle), leaving you with softer water overall.
However, if you want to be particularly careful, you could try boiling the kettle several times. While the initial boil will probably do most of the work, each successive boil may somewhat reduce the amount of limescale left in the rest of the water.
For a more energy efficient way of getting boiling water, you could water your plants with leftover water from cooking vegetables, such as potatoes.
This also adds nutrients to the soil, which some plants will love (hint: NOT carnivorous plants).
Don’t do this if you add salt to the water while boiling it.
Allow the water to cool and then splash a little into your plant’s pot and let it soak in.
However, be aware that some people have noticed this makes their home smell bad, and be prepared to rinse out the pots if you notice any lingering vegetable-y smells, preferably before they have time to turn bad.
Plants Sensitive To Tap Water
There are many plants that do not like tap water, and some that will even die if they are watered with it over a period of time – though not many are likely to keel over if they get a few drops now and again.
Spider plants are known for disliking tap water.
Some plants, like the carnivorous plants, are also sensitive to the minerals in tap water; they grow in low nutrient soils, and cannot cope with having too much nutrition around their roots.
Orchids also tend to dislike tap water. Because they don’t grow in much soil, it’s easy for the roots to get clogged up with minerals and salts, and this can make it hard for them to grow. They need lots of oxygen around their roots.
The same goes for air plants, which like plenty of oxygen, and dislike tap water.
Cacti can also be sensitive for the same reasons; they live in light, sandy soil, and therefore expect plenty of airflow around their root networks.
Some citrus plants are also not fond of tap water, and much prefer rainwater. If you can stand plants outside in the middle of a rainstorm, this is a great way to give them a well oxygenated drink (there’s a lot of oxygen in rainwater) and can also help to flush out any mineral build-up from the soil.
So to sum it up, the plants that are known to be sensitive to tap water are:
- Spider Plants
- Orchids
- Carnivorous Plants
- Cacti
- Air Plants
- Citrus Plants
Final Thoughts
Tap water is not ideal for plants, but most houseplants will be fine if you water them with it – even if you don’t let it stand to allow the chlorine to evaporate off. Many plants are pretty robust and hardy, and will put up with any sort of treatment.
However, if you notice white minerals building up in your plant’s soil, it’s time to flush them out with rainwater, and if your plant is starting to look sad and sick, it may be due to the tap water. Try and alternate with rainwater from time to time, even if you cannot fully water with rainwater every week.
Boiling tap water may help to reduce limescale to some degree, but it will not do a huge amount to make tap water mimic rainwater. However, the plants will enjoy the extra nutrients that come from any water that has been used to boil vegetables, provided it doesn’t also contain salt.
References
Home Water – A Look at Hard Water Across the US