8 Ways to Use Rainwater Effectively in Your Garden and Why You Should

Did you know that from just a small area of roof, you can harvest an impressive amount of rainwater?

What looked like a mere sprinkling from the skies, could actually fill multiple barrels and be at your disposal for targeted irrigation for days or weeks to come.

Using rainwater in your garden comes with a multitude benefits.

I’m going to explain how to use rainwater around your home and garden and the reasons you should.

Let’s get into it!

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What are the Benefits of Using Rainwater in Your Garden?

Some of the benefits of using rainwater for irrigation are the following.

Saving Money

We always like this one! If you live in an area where you have to pay for your water, not having to pay to irrigate your garden is a massive plus.

Saving Water

Municipal water supplies are often taken from groundwater sources and have to be carefully treated to ensure that the water is safe to drink. Saving this water for use inside the house rather than wasting it outside has benefits on so many levels, not least reducing the consumption of precious groundwater supplies.

water barrel in garden

Rainwater Contains Nitrogen

Rainwater collects nitrogen from the atmosphere on its way down and once that nitrogen has been delivered to the soil, it’s in the perfect place for the plants to uptake it naturally.

Reducing the Chemical Load on Your Garden

Since municipal water supplies need to be treated to make them safe for human consumption, it stands to reason that there will be residual chemicals such as chlorine and chloramines in the water.

Many town water supplies are also treated with fluoride which isn’t ideal for your garden either. Your garden will handle low concentrations of these chemicals, but it will also be better off not having to! Use rainwater for irrigation instead!

Reducing the Mineral Load on Your Garden

Groundwater supplies also have higher mineral concentrations making the water harder than rainwater.

Calcium and magnesium deposits can build up and affect the health of your garden. Rainwater on the other hand, carries negligible amounts of these minerals, making it a much healthier water source for your garden.

May Help Reduce the Risk of Flooding

If you live in an area that experiences high rainfall at certain times of the year, harvesting the water that falls on your roof can reduce the volume of stormwater runoff. This reduces the pressure on your area’s drainage system and reduces the likelihood of surface flooding.

Some urban areas in some parts of the world are starting to include rainwater tanks in the build of new homes for this very reason.

person taking water for gardening

So, now that you’re up on the benefits, are there any disadvantages?

Some Downsides to Harvesting Rainwater

Initial Investment

Setting up any new system that requires new materials will come with a cost. There are ways of keeping the cost down, such as purchasing second hand equipment and doing the work yourself. But there will inevitably be some initial investment.

I say investment, because chances are this cost will be canceled out pretty quickly by the money you save on paying for water.

Only Possible With Certain Roof Materials

Certain room materials, especially from older buildings, may leach chemicals or heavy metals into your rainwater and make it less suitable for use on your garden.

For example, if you know if there is lead, cadmium or chromium in any of your roofing materials, you shouldn’t collect rainwater that has flowed across it. If you have an old house that contains asbestos, you definitely can’t use the rainwater.

Location Near an Industrial Polluter

Another way that the rainwater might become polluted is before it even reaches your roof. If you live near a factory or an industrial area that results in air pollution, the rain may be contaminated from picking up this pollution from the air as it falls.


Depending on the system you have set up, it likely will require some maintenance at some point. Things break and need fixing or replacing, that’s just life. But hopefully, you’ll decide that the pros still outweigh the cons.

Variable Rainfall

Now that climate change has its hold on the world, the amount of rain you get at certain times will probably be unpredictable. This means that sometimes you might have more water than you need and other times not enough.

If you still have your house supply as a backup for when there isn’t enough then the benefits of using rainwater when you do have enough should still outweigh the unpredictable nature of the supply.

How to Get Started

Getting set up with a rainwater harvesting system can be as complicated or simple as you want to make it.

The most straightforward method simply consists of choosing a vessel to store the water until you want to use it and then redirecting the flow of water from your downspout into the barrel.

We have a guide to the best rainwater barrels that will help to make this decision quick and easy for you.

rainwater in black barrels

You will most likely need more than one barrel as one can fill up pretty quickly. You can link them together so that once the first is full, the overflow will continue into the next barrel and so on.

Redirecting the downspout will likely require replacing the bottom section of the pipe with a shorter length or an angled piece. This will depend on your set up and is very easy to do.

Best Rainwater Harvesting Tips


You may want to consider screening off your gutters to prevent debris from collecting and either blocking your downspout or making it into your barrel. Alternatively, screening off the bottom of the downspout will ensure that nothing inconvenient makes it into your barrel.

You could look at using something like a purpose-made gutter guard.


Aside from debris, you’ll also want to make sure that your barrels are sealed in some way to prevent them from becoming a breeding ground for mosquitoes. Covering the top with a fine mesh will prevent insects from entering and laying eggs.


Using a dark-colored barrel that doesn’t let light in and keeps the water cooler will reduce the chance of algae growing.

Keeping it free of algae and insects will play a big role in how long you can store rainwater for plant watering.

If the water is kept clean and cool, it can theoretically sit indefinitely. But you’ll probably want to empty out your rainwater tanks and give them a bit of a clean at the end of summer so you probably don’t have to worry too much about the water being there for too long.

Taps and Hoses

Be sure to have some kind of outlet at the bottom of the barrel for accessing the water, ideally letting gravity do the work for you.

The simplest solution is a tap that can be used to fill watering cans. You may need to have your barrel up on a stand so that there is room for a watering can to fit under the tap.

Alternatively, you can get more complex and set up an automated system with a variety of hoses and irrigation equipment. Options involve utilizing gravity and running a drip-feed around your garden, or setting up hoses and sprinklers with a pump that you can switch on and off.

Alternatives to your standard types of hoses that can work well include expandable hoses and metal garden hoses. They’re worth checking out for their durability and convenience!

Emptying for the Winter

If you live somewhere where the temperatures regularly drop below freezing and snow is common, emptying your rainwater tanks for winter might be a good idea to ensure that they don’t freeze and burst.

Rainwater tanks do need to periodically be emptied and cleaned anyway so this could be a good time to do it.

What Are You Going to Do With All That Water?

The most obvious use for harvested rainwater is irrigation for your garden.

But there are other uses too that come with their own benefits.

Any job that you would have used your house supply for but that doesn’t require the water to be clean enough to drink can theoretically be done with rainwater instead.

rainwater harvesting barrel

Here are some ideas you may not have thought of…

How to Use Rainwater For More than Just Irrigation

Watering Houseplants

Just like your outdoor garden, your indoor garden would far prefer mineral and chlorine-free water at an ambient temperature. Simply keep a small watering can on hand especially for your indoor plants and use your harvested rainwater instead of tap water when it’s time to water.

Keeping your Compost Moist

A healthy compost needs to remain moist for the beneficial microorganisms to do their job. Using rainwater to give your compost a wetting down when it starts to dry out in the warmer months will help ensure that your compost remains healthy.

Making Compost Tea/Liquid Fertilizer

Using chemical-free rainwater to make compost tea or liquid fertilizer to feed your garden is a far superior option and your garden will thank you for it!

If you don’t have a compost yet and are a bit overwhelmed by all the options, start small with a kitchen compost and then go from there!

Keeping on Hand for Fire Control

If you live in an area where wildfires are a risk, then having a good supply of rainwater on hand could be a lifesaver.

Washing Vehicles or Garden Tools

Washing cars is a huge waste of water at any time of year but especially during the dry season. If you have plenty of stored rainwater then you can give your car or garden tools a freshen up with this instead.

If your rainwater is clean and you have a lot of it, you could even go as far as using it in a pressure washer to give your footpath, driveway, or the side of your house a thorough blasting without using up your house supply.

young man washing car in sunlight

Keep your Pond Topped Up

The fish and all of the lovely microorganisms in your pond ecosystem will thank you for choosing rainwater over your town’s drinking water supply to keep their home topped up. Chlorine and other chemicals are the last thing you want in your pond!

Provide a Bird Bath

Similarly, the birds would far prefer a chemical-free bath in some rainwater on a hot day!

Even in winter, birds appreciate access to safe water for drinking and you’ll make your garden a lot more attractive to birds, which can be important pollinators, if you provide a bird bath.

In Your Toilet

This is probably going to be a less popular option, but as climate change grows more serious and water shortages get real, it might become a thing!

Flushing your toilet uses a LOT of water, and you can reduce this significantly simply by pouring a bucket of rainwater into your cistern and flushing with it. You don’t have to do this all the time of course, but if you have a surplus and water restrictions are in place, why not?


Hopefully, you’re feeling pretty confident about the benefits and different ways of using rainwater instead of tap water around your home and garden.

Remember, even a small roof can harvest a LOT of water, so if you want to start small, why not set up a rainwater tank next to your garden shed and see how you like it? This way, you’ll learn how to use rainwater and if it’s right for you without forking out a big investment.

Are you going to start harvesting rainwater? Or do you already have a system in place? Share your experiences with us, we’d love to hear from you!

Andy Gibson

My name's Gibson. Andy Gibson. I like to think of myself as the Bond of the backyard, that is if yard work ever became sexy. I write about everything about indoor and outdoor gardening and the dread-it-but-still-need-to-do-it chores around the yard, like cleaning out the gutter guards.

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