When you hear ‘distillation’, what’s the first thing that comes to mind? High school chemistry experiments? Medical equipment? Single malt whisky?
It might surprise you to learn that there’s a dedicated group of gardeners who consider distillation a vital part of their craft. For them, using distilled water for their plants is fundamental to keeping their collection thriving.
The urban gardening trend shows no signs of disappearing. More and more of us have caught the bug and we’re starting to seek out ever more rare and delicate plants. As the nation falls deeper down the houseplant rabbit hole, it’s undeniable that many of us could also benefit from using purified water as part of our routine.
How does water affect my plants?
Plants need water. Even desert-dwelling cacti. Even air plants growing on a log.
I don’t expect this to be news to you. After all, you’ve started looking for tips on using Water 2.0.
What you need to know is this: not all water is created equal, and the different kinds of water that we give to our plants can affect them in a variety of ways. We treat tap water with fluoride and chlorine to keep our teeth healthy and protect us from bacteria but, for plants, this can alter the pH of the soil. In hard water areas, where the water has passed through limestone, drinking water can also be especially alkaline and carries a higher concentration of calcium than soft water.
The main problem with using tap water for plants is that the trace elements in the water build up in the soil. Outside, the rain washes away these elements but, indoors, they can build up in the soil and inhibit your plants’ ability to absorb the nutrients they need to grow.
What is distillation?
Distilled water has been purified through a process of heating and cooling. We boil water and the steam rises, leaving behind the dissolved minerals as well as killing any bacteria or fungi living in the water. When the steam hits a cold surface, it condenses, and we can then collect and store the drops of pure water for our plants.
Because the distillation process removes dissolved minerals, distilled water is also pH neutral.
What nutrients will my plants get from distilled water?
While certain elements present in tap water can harm plants, they do need magnesium, potassium, and calcium (to name a few) to build new cells. If you use purified water for your plants, their only nutrients will come from the soil.
Outside, this would not be an issue as the soil is constantly replenished by natural cycles. For houseplants in pots, however, there comes a point where they absorb all the nutrients and exhaust the soil. The plants have no mechanism to replace the nutrients and deficiencies can set in.
Using pure water can still be an advantage. Though the water doesn’t give the plants nutrients, it is easy for you to fertilize them. Not only that, when you know the exact chemical composition of your water, you have total control over the nutrients your plants receive.
Using distilled water for hydroponics
When you garden hydroponically, you don’t use soil. Instead, your plants grow in a water tank known as a flood table.
Purified water is the best choice for hydroponics because, again, it provides a blank canvas for the minerals and nutrients you give your plants. With the right balance, you can expect faster growth, a higher yield, and a reduced risk of disease. This makes it a popular method for growing green leafy crops.
Naturally, in a hydroponic garden, you also have to monitor the pH of your tank and replenish the distilled water regularly. Otherwise, the biggest risk is that the water will become too acidic as it absorbs carbon dioxide from the air.
DIY Water Distillation at Home
If you have $100 – 600, you can buy a water distiller for your home. Thankfully for amateur gardeners, it’s easy to make your own.
The pot lid method
Whether it’s done in a kitchen or a factory, distilling water is a simple case of condensing steam. It’s possible to do this with equipment you already have in your kitchen – a pot, its lid, a bowl, and some ice.
The first step is to half fill your pot with water. Next, float a glass bowl inside the pot. If it won’t float, balance it on a cooling rack in the water as the bowl mustn’t touch the bottom of the pot.
Turn on the heat, turn the pot lid upside down so it looks like a shallow bowl, and cover the pot. Finally, pour some ice into the lid. The steam will rise, hit the cold lid, condense into pure water, and drip back down into the bowl.
The bottle method
Many people prefer to distil water using two glass bottles of different shapes. One must be an ordinary bottle, and the other must have a neck that curves outwards from the bottle (known to the experts as a retort distillation flask).
Start by filling your regular bottle with tap water, leaving about 5 inches at the top. Next, use Gorilla Tape to fasten the necks of the bottles together. Place the full bottle into the pot at an angle of 30 degrees and balance the retort flack outside the pot.
Fill the pot to the same level as the water in the bottle, turn on the heat, and wait for the water to evaporate from the first bottle and condense in the flask. To speed up the process, you can also place an icepack on the outside of the flask.
Storing distilled water
For safety, you should wait for everything to cool down before you try lifting your glass bowl or flask. Afterward, you should store the pure water in a clean glass container. Plastic is not a great storage solution in the long term because, over time, chemicals from the plastic will start to seep into the water and undo all your hard work.
Tap Water vs. Distilled Water
Tap water
There’s no doubt that filling your watering can straight from the tap is the easiest option. It’s cheap, accessible and most plants will be able to tolerate normal amounts of the chemicals present in the water.
If you want to make your tap water gentler on your plants, there are also things you can do. Filling a watering can the day before will give the chlorine time to evaporate and other minerals will dissipate to the bottom of the container. This is often a good half-way-house between tap water and distilled.
Distilled water
However, although purifying water yourself or making a special trip to the store to buy it can be time-consuming, there are undeniable advantages to using it.
By using pure water for plants, you prevent chemicals and salts from building up in the soil to a level that is dangerous for the plants. Even though the majority of houseplants will tolerate some chlorine, substances like calcium (present in hard water) prevent the plant from absorbing the essential trace elements it needs to build new cells. Using purified water instead can speed up the growth of new leaves.
There are also plants for which distilled water is essential. A good example is air plants, They are extremely sensitive to the chemicals used to treat tap water and to give them their regular misting with anything other than pure water is to put them at risk.
Even plants that we think of as hardy can be vulnerable to chlorine and fluoride in water. Anything with a slender leaf, such as spider plants, dragon plants, prayer plants, and even aspidistra (often thought of as impossible to kill) can end up with scorched leaf tips or brown spots from being watered from the tap.
Final Thoughts
While watering all of your plants with purified water may not be necessary, it is something to consider for some of the most popular houseplants of the moment. If nothing else, you should research your local water supply to help you make a decision. Consider whether you live in an industrial area with acidic water, a hard water area, or a municipality that uses a high dose of chlorine.
Never forget, though, that you should also have fun. Most gardeners are curious people, and the idea of cooking up some pure water or even giving hydroponics a try can be appealing. Even if your plants are not particularly vulnerable, you’ve got nothing to lose by trying something new.