Does rainwater have nutrients?

We have talked a lot about the benefits of installing a rainwater tank at the home or at a commercial property. We often focus on the benefits they bring inside the property – helping to reduce your water bill and providing a sustainable source of water for your home or workplace. Another big benefit of installing a water tank to collect rainwater from your roof is for your garden. Rainwater is full of nutrients which many people believe to be better for watering your plants and grass than using tap water from the mains supply.

Rainwater is known to contain many nutrients that are great for your plants and garden. Nitrogen, phosphorus, potassium, calcium, magnesium, and sodium have all been detected in rainwater.

Nitrogen, in particular, is a well-known nutrient for plants, often found in fertilisers, helping to foster the growth of plants and vegetables. Often you will notice that plants are much greener following heavy rain, even if you water your plants on a regular basis using tap water. This is because nitrates are more easily and readily absorbed from natural rainwater.

Is rainwater good for plants?

As you might have guessed, the simple answer to this is yes! Whilst your outdoor plants benefit every time it rains, the same can’t be said for your indoor plants.

Collecting rainwater, either in a barrel or in a larger rainwater tank that can be used to supply water inside and outdoors, is a great way to provide your indoor plants with a natural nutrient boost every time you water them.

During the dry summer months, many gardeners turn to their water tanks to keep their gardens looking in the best possible condition. Collecting rain during the wet winter months is a great way to store nutrient-rich rainwater for use in the dry months, helping to keep your plants and garden looking great all year round.

Why is rainwater better than tap water for your plants?

One of the main reasons why rainwater is better for your plants than tap water is the chemical makeup of both.

Whilst rainwater is known to contain nutrients that are beneficial to your plants and vegetables, tap water contains chlorine which is an important disinfectant, and fluoride, which helps to prevent cavities in your teeth.

Unfortunately, neither chlorine nor fluoride is great for your plants. Plants are susceptible to chlorine and fluoride toxicity. This might manifest itself in the form of burnt or spotted leaves.

Magnesium and calcium are also present in mains tap water. This leads to “hard” water (more on that below) which can cause issues with your pipes. To prevent water from becoming too hard, sodium is often added to tap water to “soften” it. Sodium, along with magnesium and calcium can all cause issues for plants, as well as the soil structure.

Rainwater, on the other hand, is rich in nutrients including nitrogen. Drops of rain are also rich in oxygen which helps to stop roots from becoming waterlogged, leading to root rot.

Benefits of rainwater for plants

Whilst we have touched on some of the benefits of using rainwater to water both indoor and outdoor plants, here is a comprehensive list of benefits:

· Supplies natural nitrogen for greener plants

Rainwater contains a small amount of dissolved nitrogen in the form of nitrates and ammonium which plants can absorb.

· Helps to balance the pH level

Rainwater is a little acidic and tends to fall on the right side of the pH scale, at around pH 7. Ideally, plants love to grow in soil that is around pH 5.5 to 6.5. Tap water tends to be much higher, around 8.5 to 10.5 on the scale which can be harmful to plants. Rainwater helps to balance this out, especially during the summer months when plants are more reliant on additional watering when there is less rainfall to water them naturally.

· Rainwater is soft

Unlike tap water, which often has sodium added to it to soften it, rainwater is naturally soft which makes it much safer for plants. Rainwater contains virtually no minerals and no chemicals, making it a much safer option for watering your plants.

· Rainwater is free

Once you have installed a method for collecting your rainwater, it is a free resource that is continually renewing. This helps to cut down on your water bills, as well as helping to reduce the strain on the mains water supply. During particularly warm summers, when watering bans can be enforced, collecting rainwater also means you can water your garden all year round.

· A natural fertiliser

When we collect the rainwater that falls onto our roofs, it collects debris as it makes its way into whatever storage system you have set up. Whilst most of this debris is filtered out, small amounts of organic matter make their way into the water supply. When this is then applied to plants and the garden, you are adding a light application of natural fertiliser to your plants.

Collecting rainwater

Rainwater collection has become much more popular in New Zealand over the past decade. Whilst water tanks were once a common feature of all houses in NZ, especially in remote locations with no access to mains water, they are once again making a resurgence as people start to think more about the environment and living a more sustainable life.

Since the water restrictions in Auckland in 2020, a lot more people have also turned to water tanks as a way of ensuring they have a constant water supply throughout the year. Whether that’s simply for watering the garden, cleaning the car or providing water for the entire home, having access to clean, green water has become much more appealing to New Zealanders.

We have written a number of articles about not only the benefits of collecting water but also the best way to collect water and the different types of tanks.

At Smart Water, we are helping more people to start their journey into collecting rainwater. One of the biggest barriers for people adding a rainwater tank at home is the uncertainty of not knowing how much water is left in your tank. This applies to rainwater tanks stored both above and below ground.

At Smart Water, we have engineered the most advanced tank level indicator available that now offers full cloud connectivity.

Easy to install yourself, your Smart Water tank indicator provides you with all the information you need from our app or from one of our LCD displays. Find out how much water you consume on average from your tank, accurate pressure data and estimates on when your tank will run out of water based on current usage.

Find out more about our range of products or check out our FAQs for more information.

· Collecting and using rainwater – a beginner’s guide

· How much rainwater can you harvest from your roof?

· Is rainwater harvesting worth it?