How to Make Tap Water Safe for Plants
Water quality is something often overlooked by houseplant enthusiasts. It's easy to think tap water is inherently safe despite many municipal water sources not being the best for plant growth. While tap water won't usually kill your plants, depending on your source, it can impact their vigor and overall health.
Not all water is created equal. Water quality can vary significantly within the same city or municipal water system. Where it comes from, how it's treated, and even its transportation can all influence the water quality from your tap.
Thankfully, you can treat even the worst tap water with simple tips and tricks. In this article, we'll discuss what to watch out for in tap water and how to improve its quality if necessary.
Is tap water safe for plants?
Generally speaking, tap water is safe for most plants. Given adequate conditions, plants will do fine and thrive with tap water. Some tap water sources can be particularly harsh on plants, and certain plant varieties can be highly sensitive to their water source. Generally speaking, most plants will grow better and healthier using the proper water.
Common factors that affect tap water quality for plant health
Hardness (calcium & magnesium)—Tap water and some well water sources can both be hard, meaning they contain high levels of calcium and magnesium. While not inherently bad, hard water can gradually raise the soil's pH and make it alkaline. Since most houseplants prefer slightly acidic soils, a higher pH over time can considerably impact their health. While it may not be obvious by tasting it, evidence of hard water is often seen in the accumulation of calcium in water kettles and other areas where water has evaporated.
Chlorine and chloramine—Most municipal tap water sources use disinfectants like chlorine and chloramine. These ensure the water is safe for drinking and does not contain potentially harmful or pathogenic microorganisms. While many plants tolerate these disinfectants, they can be harsh on house plants by disrupting the beneficial soil biology and, in some cases, directly damaging root hairs and hindering nutrient uptake.
Salinity—While salinity is not often an issue for most outdoor gardeners, it can become problematic over time for indoor potted plants. Small amounts of salt in your water source can build up in the soil and negatively affect nutrient and water uptake.
Contaminants—While tap water is typically treated and regularly monitored for contaminants, occasional traces of contaminants, including agrochemicals, heavy metals, and a whole assortment of other compounds, can occur. While these probably won't occur in significant enough quantities to affect plant health, they certainly won't help.
Fluoride—While most plants tolerate fluoride just fine, certain varieties can be particularly sensitive to fluoridated water.
Hard water vs soft water for plants
As previously mentioned, hard water is particularly rich in calcium and magnesium. Due to the presence of these minerals, hard water is alkaline and often has a pH ranging from 7 to 8.5. Soft water is the opposite, meaning it is largely void of these minerals and tends to have a pH between 6 and 7 (acidic). Soft water tends to be more saline.
While it may seem beneficial to have minerals like calcium and magnesium in your water, it doesn't offer nutritional benefits to your plants. Hard water can, over time, raise the pH of your soil and make it difficult for plants to absorb nutrients. Plant roots require a specific pH range to grow and acquire nutrients from the soil. Most plants prefer slightly acidic soil, with a pH between 5.5 and 6.5.
Hard water is common in many parts of North America and occurs in over 50% of households. The easiest way to tell if your water is hard is to check your municipal water source's water quality report. Evidence that your water is hard is often visible as a white mineral buildup around faucets, showerheads, or kettles after boiling water.
How does tap water affect plant growth?
While it can often be challenging to know whether your water or something else is affecting your plant health, there are sure signs you can look out for to help diagnose your issue. Sometimes, it may take months, or even years, of using tap water for these issues to become prevalent. Below, you'll find several reasons tap water is bad for plants.
- Browning tips or edges on leaves can indicate mineral buildup from hard water for chlorine damage.
- Yellowing leaves, especially between the veins, can indicate nutrient deficiencies caused by imbalanced mineral content or high pH from using tap water for extended periods.
- Stunted growth - If your plants seem to be growing slower than usual, it could be due to improper watering, including using unsuitable water.
- Overall decline - A generally unhealthy appearance, with drooping leaves, lack of new growth, and possibly even leaf drop, can be a symptom of water quality issues.
- Visible salts - A white crust accumulating on the soil surface can indicate a buildup of minerals from hard water or tap water without proper treatment.
Plants sensitive to tap water
- Ferns—Ferns are highly sensitive to chlorine and chloramine in tap water. These chemicals can damage their sensitive root systems and hinder nutrient uptake.
- Orchids—Orchids prefer slightly acidic water. The higher pH of hard tap water can stunt growth and cause leaf discoloration.
- African violets—These popular houseplants are sensitive to chlorine and mineral buildup from hard water. Leaf browning and stunted growth are common signs of tap water problems.
- Citrus trees—Citrus trees prefer slightly acidic soil and can develop issues like leaf chlorosis (yellowing) if consistently watered with tap water, especially hard water.
- Coffee plants—Coffee plants thrive in slightly acidic conditions and can be sensitive to the higher pH of tap water, potentially leading to stunted growth or leaf yellowing.
- Spider plants—While known for their hardiness, spider plants can develop brown leaf tips if watered consistently with tap water high in fluoride.
- Calatheas—Calatheas appreciate consistent moisture and slightly acidic soil. Tap water can disrupt this balance and lead to problems like leaf curling or browning.
- Prayer plants—Similar to Calatheas, prayer plants prefer slightly acidic environments and can be sensitive to tap water's mineral content and pH.
- Azaleas—These acid-loving flowering plants can struggle with the higher pH of tap water, potentially leading to nutrient deficiencies and stunted growth.
- Dracaenas —These popular houseplants can develop brown leaf edges over time due to mineral buildup from tap water.
- Peace lilies can experience leaf tip burn if watered exclusively with tap water due to accumulated minerals.
Is well water safe for plants?
Like tap water, well water can significantly vary depending on your location. After all, well water is simply groundwater naturally filtered through the native rocks and soils. The composition of these soils and rocks can impact the makeup and quality of well water.
The biggest drawback of well water is its often high mineral content. In some cases, it has high quantities of magnesium and calcium, causing it to be hard water.
Another risk of well water is that it can be contaminated with heavy metals and agrochemicals. If you live in an area with a history of industry or agriculture, having your well water tested may be worthwhile.
That said, some well waters can also be exceptionally clean. The water is filtered through the ground, sometimes for decades, meaning it can be much cleaner than surface water sources. Another great benefit is that if you have a local well, it likely isn't chlorinated.
Best water for houseplants: rainwater
Rainwater's natural composition is among the best you can utilize for watering your plants. It's free of salts, minerals, and disinfectants and has a slightly acidic pH that plants love. While it can be vulnerable to air pollution, rainwater tends to be free of other contaminants.
How to make tap water safe for plants
Thankfully, in most cases, you don't need to buy fancy equipment, haul in water, or build a rainwater catchment system. The quality of your tap water can be improved using a couple of easy tools and techniques.
How to dechlorinate tap water for plants
Most old-school gardeners know that you can dissipate chlorine in tap water by leaving it out for 12-24 hours or boiling it. While this technique works, it's important to check if your municipal water system contains chlorine or chloramine. Chloramine cannot be easily removed from tap water, and today, it is just as commonplace as chlorine. Some water systems may switch back and forth between the two.
Best water filter for plants
A high-quality carbon filter is often good enough to filter chlorine, chloramine, and other contaminants. It can be a practical option, although it can get expensive if you want to filter substantial quantities of water. You can use a simple countertop version or install one under the sink.
Tap Water Conditioner: the easy solution
One of the easiest ways to improve tap water quality is to use a water conditioner, which is 100% safe and can be mixed into your existing tap water. These conditioners neutralize both chlorine and chloramine and reduce mineral content via chelation. They also help maintain a healthy pH that keeps your plants thriving.
Southside Houseplant Tap Water Conditioner is an excellent option for anyone interested in a water conditioner. A single bottle can treat 16,000 gallons of tap water, so it can last most plant enthusiasts for years.
Conclusion
Using high-quality, properly treated water can make tremendous differences in the health of your plants. It usually takes 3-4 weeks to start seeing the benefits, but in some cases, it is much quicker. This is particularly true if you've been unknowingly raising the pH of your soil after years of watering with hard water.
Also, you may finally be able to grow the plants that have been giving you trouble for years. A little knowledge goes a long way in ensuring your leafy friends flourish and bring you joy for years to come!