Is It Okay To Use Reverse Osmosis Water For Plants?

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Reverse osmosis, also known as RO or R/O, is a water purification process that uses technology identical to ultrafiltration.

This process removes a wide assortment of contaminants (ions and molecules) that are usually found in private as well as public water supplies.

Some of these contaminants include bacteria and microorganisms which are harmful to the growth of plants.

This process is used in industries mainly to clean wastewater before distributing it as well as desalinating sea, brackish or open water.

Basically, reverse osmosis can be applied in any situation which involves getting rid of solid materials. A well-made reverse osmosis system can remove between 95 and 99% of particles and contaminants.

Reverse Osmosis Works

For reverse osmosis to work, you first need to add water into a reverse osmosis system so it can first pass through a sediment filter to remove some of the large, harmful particles and contaminants. After that, it needs to go through a semipermeable membrane for the smaller particles.

This membrane was designed to prevent the flow of virtually every microorganism, metal, particle, and other random particles. As a result, we get safe and clean drinking water.

The only thing it has trouble with is transferring dissolved gases. But it is effective in removing virtually any unwanted or for material from passing through.

The rate at which the materials passed through is commensurate and proportionate to the type and size of the membrane, as well as how polluted the water is as well as its flow rate.

During the reverse osmosis process, the pressurized side of the semi-permeable membrane is where the solute is kept, whereas the solvent forcibly passes through it.

Only smaller molecules or particles can pass through the membrane while holding the larger ones back.

Now that the solution is concentrated, pressure needs to be applied so that water can go through the semi-permeable membrane. You can even use a pump to help water, as well as smaller particles, go through the membrane’s tiny pores.

RO systems these days are typically installed using a crossflow just so the membrane continuously cleans itself. This means that the particles that didn’t go through the membrane, will be disposed of.

Distillation is another form of water purification. If you want to find out more about the differences between it and reverse osmosis water, simply click here.

You May Also Read: How to Build a Hydroponic Garden? – Complete DIY Guide (With Pictures)

Can RO Water Be Used on Plants?

Now comes the part where we asked ourselves, “is reverse osmosis water good for plants?”

One of the biggest gripes of reverse osmosis water is the fact that it removes large particles and molecules, some of which are actually essential for the growth of plant life.

That’s not much of a problem considering that we can actually add some of those minerals into the water just so we can water our plants. But now one of the biggest mysteries to tackle is whether we can use reverse osmosis water for plants. Now let’s find out.

If you want to grow healthy plants and have them thrive well, then you need to strike the right balance in their nutrient-intake.

Unfortunately, conventional water (or foul water) consists of a number of impurities or contaminants, which disrupts the balance of nutrients that plants require.

Thankfully, with reverse osmosis water in our possession, we can provide our plants with the cleanest water possible without any of the harmful contaminants or chemicals at their growing stage.

Doing this also allows us to accurately calculate the balance of minerals, and get rid of any potential reactions if we ever use chemically-enhanced fertilizers.

Of course, RO water does come with its share of disadvantages, in which one of them includes copious amounts of water which is wasted.

If you’re watering a huge garden, you’ll find that your water bill will go up simply by turning regular water into RO water. Tap water of up to 3 gallons is required to make one gallon of clean drinkable water on average.

So that’s plenty of water which is wasted when we switch over to reverse osmosis systems.

Another downer is the lack of salt that some plants require in order for them to properly grow. To compensate for this, some people use fertilizer salts. For reverse osmosis water, the right quantity of salt required is 1 teaspoon per gallon.

Growers are especially fond of RO systems as it allows plans to get a proper dosage of plant nutrients. With no dissolved solids and particles in the mix, there are virtually zero chances of electrical conductivity.

This means that growers don’t have to worry about which ions are already in the RO water that may bind with, as well as render some of the added nutrients useless or even forcibly multiply nutrients which could cost nutrient toxicity.

You must be aware of the possible corrosive nature of RO-treated water. To counter this, you should use some of the dissolved magnesium and calcium in untreated, hard water which will prevent the pipes from corroding. Now with the hardness gone, RO-treated water can eat away galvanized or copper pipes a lot quicker than if it weren’t treated.

That’s why growers have to ensure that their irrigating with RO water just so the watering line can tolerate relatively pure water.

When to Use Reverse Osmosis for Plants?

The answer lies in the current TDM of our water. If the reading is around 150 PPM, we recommend switching over to RO to achieve better plant growth.

That’s because 150 PPM means that plants are having a harder time absorbing the positive minerals and nutrients. You also must ensure that the TDM level isn’t high, which is about 300 PPM.

That is 1000 TDM if we were to inject 700 TDM of nutrients into the water. You must avoid this level as it could result in salt up and nutrient lock-up, which is harmful to your plants.

Also Read: Identifying House Plants: 3 Best Ways


So overall, is it alright for us to be watering plants with reverse osmosis water? We certainly believe so. Despite a couple of its disadvantages, it can still be managed and allow our plans to enjoy the benefits of RO water.

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