The water you give to your house plants matters. While you may not need to fill your watering can with Evian, there are steps you can take to ensure that your water is safe and healthy for your plants. From the drought-tolerant Desert Rose to the thirsty Calathea, even resilient houseplants will benefit from proper watering. In this article, we’ll show you exactly how to do it.
The Problem With Tap Water
Look, tap water isn’t poisonous. However, there are added chemicals and processes that affect tap water quality and can have a negative effect on your houseplants.
There are a few different chemicals that are sometimes present in tap water, notably chlorine, fluoride, limescale, and pH additives. Excess chlorine can be harmful to plants, while certain plants are especially sensitive to fluoride. Plants with long, narrow foliage such as Spider Plant, Peace Lily, Dracaena, and Prayer Plant can be negatively affected by tap water high in fluoride.
Plants also prefer their water at a pH level between 5.0 and 7.0. Often, a high pH level won’t harm houseplants as long as alkalinity is low, but if both the pH and the alkalinity are high, it could lead to nutritional disorder in plants.
There is always a danger of having contaminants in your water. Don’t worry, we’re not trying to scare you. It’s unlikely that contaminants in your tap water will reach levels unhealthy enough to hurt you or your plants. That said, waterborne contaminants include bacteria and viruses, aluminum, copper, lead, nitrates, and perchlorate.
Tap water can be hard or soft, and softened water is extremely detrimental to plants. The process of softening exchanges the calcium and magnesium in water for sodium. While calcium and magnesium are nutrients for houseplants, sodium becomes toxic to plants over a period of time. So, if you recently moved or brought your plants inside for the winter, softened water may explain while they’re doing poorly.
Signs of Poor Water Quality in Plants
There are several signs that your plant may be suffering due to poor water quality. High pH can lead to iron deficiency, which can then lead to leaf chlorosis. This means your plant’s leaves will turn yellow while the veins remain green.
Meanwhile, those high sodium levels we described will attack a plant's roots, leaving it looking wilted and sickly, while slowing growth. If you notice that your soil has a white, crusty buildup on the surface, it’s a clear sign of salt buildup.
Making Tap Water Safe for Houseplants
There are a few methods you can take to make your tap water safe for use on houseplants. Some are very easy—you don’t need to be some kooky chemist to make tap water safe. Other methods are a bit more difficult, but will also pay off in the end.
Let Your Water Sit: The easiest way to make tap water safe requires one thing: planning. Run your sink into a watering can, cup, or bucket, and let it sit for a good 24 hours. This will allow chemicals like chlorine and fluoride the time to evaporate from the water. We like to have a full watering can ready to go with still water so that if our soil seems dry, we can water our plant without waiting a day.
Reverse Osmosis: Reverse osmosis is a technological process used to remove contaminants from water, including calcium, fluoride, iron, and lead. The water passes through a system that catches impurities. Some liken reverse osmosis filtered water to having rainwater come from your faucet. However, reverse osmosis systems can be expensive, so they may not be right for more casual gardeners.
- Change the pH: If you notice that pH levels in the water you're using are too high or too low, there are ways to balance it out. If it’s too high, you can try adding vinegar to your plant’s water once a month. Vinegar is acidic and will help balance the pH level. Lemon juice will also help in a similar fashion. Meanwhile, to raise the pH you’ll have to add substances that are more basic. Try adding limestone or wood ash to your water. You can also counter undesirable pH levels with soil that is high or low in pH. Fertilizers containing sulfur will lower pH levels, while those containing lime or dolomite will increase them.
Alternatives to Tap Water
Rainwater: Rainwater is one of the few types of water that is naturally soft. Do we really need to convince you that rainwater is good for plants? There are literally millions of years of evidence. It’s the best source of water for your house plants, period!
Bottled Water: Bottled water is great to use if your tap water isn’t turning on, or is contaminated in some way. Besides special circumstances, it can become too expensive and environmentally destructive to be used as your primary watering source.
Distilled Water: Like premium vodka, you’ll want to distill your water at least five times for your Philodendron to be satisfied. Just kidding. While distilled water is definitely one of the preferred types of water for plants, it’s asking a bit much of an average gardener to buy a water distiller for their home. Still, if you want to go for it, we applaud you!
Aquarium Water: Changing the water in your fish tank? Don’t dump the old stuff down the drain—use it on your houseplants instead! There are tons of healthy nutrients and minerals in aquarium water that will help your houseplants thrive. The only downside is while you’re watering the plants, your fish may try to escape back to the ocean. Did they ever end up finding Nemo?
Tips on Watering Houseplants
Different plants have different watering needs, so it’s important not to lump them all together under the same “house plant” umbrella. After all, these beautiful plants didn’t grow in your living room—they come from a vast array of environments, from tropical rainforests to arid deserts. Tropical houseplants like Alocasia or Swiss Cheese Vine will require far more water than a Madagascar Palm or Peruvian Apple Cactus.
Here are a few watering tips before you go:
- It’s better to water plants in the morning as opposed to the evening. This way they have time to dry and absorb water before nightfall.
- Watering with room temperature water is ideal. It’s preferable to use water on the warmer side than the colder side, because cold water may send plants into “winter mode” and slow their growth.
- Overwatering is one of the main causes of house plant deaths. New gardeners will tend to overwater, but play it safe and fight off the urge to do so. Use a moisture meter to know exactly when your plant needs a drink.
- Don’t continue the same watering schedule all year long. Most plants need more water in the summer than they do in the winter, so cut down on watering when the weather cools down.
- Pour your water directly onto the soil. We know when we were young and naive, it seemed logical to pour water over your plant’s leaves as if giving them a shower. Once we almost washed them with a bar of soap. But plants aren’t like us. Splashing water on the leaves can damage a plant. The water can collect on the leaves and cause them to rot.
Well, that’s all we have for today! Now go enjoy a cold glass of water and don’t forget to share it with your favorite house plant. Just let it rest for 24 hours first.