When you install a water softener in your home, you don’t only benefit from soft drinking water. The water you use to cook with, shower in, wash clothes with, and just about everything else will also be calcium and magnesium-free.
But is soft water beneficial for all occasions? Should you use soft water for watering your outdoor and indoor plants? We’ve shared everything you need to know in this guide.
Soft water should be fine to water your plants with, but you can choose to use hard water if you’re worried about the higher levels of sodium in your softened water.
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🚿 Is Soft Water for Plants Safe?
Yes, softened water is safe to use to water your outdoor and indoor plants.
Why? Because soft water is free from dissolved minerals, and contains only small amounts of sodium. That’s why drinking softened water is also completely safe.
The actual water quality of soft water is very similar to rain water. Rain water is formed by evaporation, so it’s pure and mineral-free. The key difference is that softening water with a softener adds salt to the water. Plus, household water often contains traces of other contaminants, like chlorine.
Although sodium isn’t a mineral that’s generally needed by plants, it’s often found in the soil, especially near the coast. For this reason, most plants can tolerate sodium – and it’s thought that small quantities of sodium may aid the synthesis and metabolism of chlorophyll.
With that said, using softened water to water your plants is recommended as a short-term solution only.
Related: What is the pH of soft water?
⛔️ Potential Issues with Watering Plants with Soft Water
While watering your plants occasionally with softened water should be fine, there are several potential issues linked to long-term plant watering with soft water:
Salt Will Build Up in the Soil
If you water your plants every day with softened water, the sodium chloride in the water will build up in your soil. This is unlikely to harm your plant, but it may affect the structure of your soil, especially if you live in a dry region where rain is infrequent.
You’ll Increase your Water Softener Costs
Using softened water to water your plants could get expensive if you have a large garden that requires daily watering. Every time you take water from your faucet, your water softener system will need to soften another batch of water. Over time, this could add up to hours of extra use per year, significantly contributing to your energy bills.
📝 Alternative Forms of Water for Watering Plants
If your entire home is supplied with softened water, there are a few alternatives to consider for watering your plants:
A Separate Outside Tap
The most convenient source of water to water plants in outdoor gardens is an outdoor tap that’s connected to your mains, upstream of your water softener.
Having an outdoor tap means you can simply turn on the tap and collect untreated water in a matter of seconds.
Rainwater is another good choice for watering your plants, and often contains helpful plant nutrients that will encourage healthy growth.
It’s easy to collect rainwater – just put a bucket, a container, or even a plastic garbage can at the base of a downspout. When it rains, the water will collect in the container, rather than going down your drain.
The only setback of collecting rainwater is that the water tends to run out in the warm, dry summer months, right when you need it the most.
Most water softeners utilize potassium as well as sodium nowadays – and both minerals serve the same process in the ion exchange process. Potassium is a more beneficial plant nutrient than sodium, and can be used as a natural fertilizer to speed up plant growth.
To safely water your plants and decrease your own daily sodium intake, consider swapping sodium for potassium chloride in your water softener system. You’ll need to set your water softener’s hardness setting 20% higher when using potassium, as it isn’t quite as efficient as salt.
This isn’t the most convenient alternative to softened water for watering plants, but you can access untreated water by activating the bypass valve to divert hard water around your water softener. This means that, while the softener is bypassed, you’ll have access to hard water.
The problem with this method is that your tap water will be hard, which means you’ll have hard water flowing though your hot water heater and all your pipes. While this won’t reverse all the benefits of your water softening system, it means that your home won’t be completely protected from limescale.
Salt-Free Softened Water
One option you may not have considered is to remove the salt from your softened water.
Salt is difficult to remove from water, and a standard water filter won’t cut it. The best way to remove salt from water is with a reverse osmosis water filter. RO water filters use a semi-permeable membrane to virtually eliminate sodium from salt water. That’s why reverse osmosis is commonly used for seawater treatment.
Distillers are another method of removing salt from softened water. Distilled water is just as pure as reverse osmosis water, so it’s a good way to give your plants the hydration they need, without the unwanted chemicals or minerals.
You can buy both distillers and reverse osmosis water filters for at-home use.
Our least recommended alternative to softened water is to water your plants with bottled water. This is a more suitable method for house plants – for outdoor watering, it’d get expensive, fast.
Many bottled water products are treated with reverse osmosis and other filtration methods to make them pure. Pure water is ideal for plants, but we still don’t think it’s worth the money spent and plastic wasted. If you want to use pure water on your plants, it’s best to purify it yourself.
🧠 Can I Water My Plants With Soft Water? FAQs
Is naturally soft water safe to water plants with?
Yes, naturally soft water is safe to water your plants with. That’s because this water hasn’t been softened with salt, so it won’t contain any sodium ions that will build up in the soil.
Is it bad to water plants with softened water?
No, it isn’t bad to water plants with softened water. However, it’s best not to, due to the buildup of sodium in the soil. If you can, use water from an outdoor tap that’s connected to your water supply line upstream of your water softener.
Is it better to water my plants with boiled hard water?
It depends on whether your water contains temporary or permanent hardness. Boiling water will remove temporary hardness, but only water softeners can remove permanent hardness.
Is potassium chloride safe for plants?
If you soften water with potassium chloride, not sodium chloride, potassium chloride is also safe to water plants with. In fact, potassium is a common plant fertilizer, encouraging faster, greener growth.
Is hard water good for plants?
Yes, hard water is good for plants as it contains minerals that are important for plant growth and development. However, hard water is highly alkaline, and some acid-loving plants, like begonias and azaleas, struggle to grow in alkaline conditions.
Will soft water kill grass?
No, soft water doesn’t contain enough sodium to kill plants or grass. However, if you empty the brine solution from your water softener onto your grass, this is likely to have some negative effects, as brine contains a much higher salt content than soft water.
Do plants tolerate chlorinated tap water?
Some plants tolerate chlorinated tap water, and others don’t. It depends on the type of plant. If your water has a strong chlorine taste, let it sit in your watering can for several days, which will cause the chlorine to naturally dissipate, improving your water balance.
Can I water indoor house plants with soft water?
Yes, house plants can safely be watered with softened water. However, with the aim of keeping indoor plants happy, you might want to use untreated tap water or rain water to prevent salt from affecting the quality of the soil.