Is it best to use tap or distilled water for indoor plants?
It’s pretty safe to say that most people understand that plants need water if you want to keep them alive. But water quality varies massively and can impact the health of your houseplants. So should you use tap water, rainwater, distilled or filtered water for houseplants?
Different Types Of Water For Houseplants
Whilst tap water will do fine for most plants, there are many other options you can consider. Tap water is usually the easiest option, and will be fine in most situations. The water quality of the other choices will usually be better, but only necessary to maintain plant health in certain circumstances. Let’s look at the options.
To help choose the best type of water for your houseplants let’s talk about the different types of water and the pros and cons of each.
Tap water
For most people, tap water is a staple in their homes, and they give little thought to having access to it. We simply go over to the faucet, turn it on, and have an unlimited supply right at our fingertips. Depending on your location the tap water will either be fed via a well on your property or is supplied through pipes connected to your local water facility.
Tap water can be classified as either “hard” or “soft”, depending on its mineral content. Rainwater is naturally soft, containing few minerals, as it falls; as it works its way into above-ground and underground water sources it picks up minerals such as calcium and magnesium, making it hard. This hard water can be softened again using potassium or sodium ions to replace and eliminate the calcium and magnesium.
Pros Of Tap Water
- Most people have low-cost, or free, access to tap water.
- Water quality standards are set in place to regulate public drinking water supply.
Cons Of Tap Water
- Public drinking water contains chlorine and fluoride in some areas.
- Calcium and magnesium in hard water build up in the potting soil and can create a layer on top that repels water.
- Sodium in soft water can quickly reach levels toxic to plants since it isn’t a plant essential nutrient. When high levels of sodium ions accumulate, it creates a sodic soil that may have problems with water infiltration and alkalinity.
Bottled/Spring water
A common staple in some homes, bottled water is another source of water for houseplants. Water from underground sources works its way to the surface and is then collected for bottling. Depending on the natural mineral content it can be labeled spring water or mineral water.
Pros Of Bottled Water
- Bottled waters may contain minerals such as calcium, magnesium that are needed by plants, depending on the water source.
- They do not contain contaminants, including chlorine and fluoride.
Cons Of Bottled Water
- Price can quickly add up if you have numerous houseplants.
- Plastic containers add to landfills or need to be recycled.
Distilled Water
Distilled water is a type of highly purified water that is free of contaminants and impurities. Water is boiled to create steam/vapor and then condensed back into a liquid to be collected in a separate container.
Pros Of Distilled Water
- Free from minerals (calcium, magnesium, and sodium), using distilled water for your houseplants prevents buildup on the soil surface that may impact water infiltration.
- Peace of mind that there are no harmful chemicals that can impact the health of your plants.
Cons Of Distilled Water
- The distillation process removes minerals such as calcium and magnesium that can be used by plants.
- Higher cost because of the manufacturing/distillation process.
Rainwater
Ah, rainwater…the original source of water for crops and plants.
Pros Of Rainwater
- The only associated expense is collection containers.
- Naturally soft water, containing low concentrations of calcium and magnesium; free of chlorine and fluoride.
Cons Of Rainwater
- Hard to collect in areas with low precipitation levels. It may not be feasible for apartment dwellers or those in highly populated urban areas to collect rainwater.
- Rainwater is naturally slightly acidic, but water collected in areas of high manufacturing may be highly acidic due to pollution and acid rain.
Recommendation For The Best Water For Houseplants
We’ve covered why water quality is important, the components of water that affect plants, and the different types of water. But now let’s get down to choosing the best water for houseplants.
I believe that tap water is fine to use for watering most houseplants. Be aware you may see problems if the plant is overly sensitive, or you live in an area where the tap water has quality concerns such as a particularly high mineral content or contains chlorine, fluoride, or heavy metals.
I suggest using tap water first in most situations and carefully observing for any adverse effects: scorching of leaf tips, necrotic tissue, chlorosis, or a significant buildup of salt on the soil surface that repels water.
If adverse effects are seen and you suspect your water quality is the cause of the problem, then take steps to improve the water quality if feasible, or use rainwater/distilled water and watch for an improvement in the condition of the plant.