How to Capture Rainwater for Gardening

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A major issue backyard gardeners come across is fulltime access to water. If you don’t have a water facility readily available, it can become challenging for your plants to receive the water nutrients they require. With water shortages and droughts also prevalent issues, we need to become more innovative in the way we water our plants.

A prominent solution to such an issue is utilizing rainwater. Installing a rainwater collection system also conserves potable water, i.e., the water that is safe to drink. Whether you may be interested in saving a few dollars, or preserving drinkable water, harvesting rainwater for gardening may be the solution you’re on the lookout for.

How to Capture Rainwater for Gardening
lemon plant in rainwater

Did you also know that approximately 600 gallons of water can be harvested from one inch of rain if it falls from a thousand square foot roof? That’s a lot of water! Unfortunately, the process is not as easy as it seems.

It requires capturing, storing, and transporting rainwater wherever needed. However, we’ve broken it down for you. With these simple steps, you can utilize rainwater for your vegetable garden, flowers, livestock, and even drinking purposes.

Read on to find out how you can capture rainwater for gardening:

How Soil Stores Water

Not many people are aware of just how much water soil can essentially hold. Your garden soil will probably never be at ‘field capacity’ – a term used to describe the maximum amount of water soil can hold. When we water our plants, gravity pulls down all the liquid into the soil.

After heavy rainfall, some of the water moves down to the water table or bedrock, but capillary forces hold a significant amount. These forces cause the water to fill water between each soil particle. It is through these forces that your plants receive the water they need to grow.

The field capacity in each soil varies depending on how much sand it includes. For instance, one cubic inch of course sand may contain approximately 125,000 particles, whereas the same amount of finest silt could have 15.6 particles.

The numbers mentioned above imply that there are soils that can hold up to 2 to 3 inches of water in each foot of soil depth. They also indicate that garden soil that contains tons of organic matter can possibly hold even more water. Crop roots extend underground anywhere between 4 to 8 feet deep to get access to capillary water.

To reinforce this system, gardeners often keep soil moisture to a depth of 4 feet, at least. The more water that is stored in the soil, the less need there is for supplementary irrigation. Hence, this means that a rainwater collection facility automatically ensures the soil remains consistently moist for the crops to receive abundant nutrients.

Yearly State-Wise Precipitation

There are ways to calculate the amount needed to capture rainwater for gardening. If you are using your roof, it is important to know the measurements of the area connected to your rainwater collection system.

Furthermore, it is also essential to understand how much it rains in your area. If precipitation levels are not up to the mark, your rainwater collection system may be of no use. On the other hand, if annual rain levels are significant, your crops may be at an added advantage. 

Below is a table of yearly state-wise precipitation:

Name of StateAvg. Total Yearly Precipitation (in.)
Alabama58.3
Alaska22.5
Arizona13.6
Arkansas50.6
California22.2
Colorado15.9
Connecticut50.3
Delaware45.7
Florida54.5
Georgia50.7
Hawaii63.7
Idaho18.9
Illinois39.2
Indiana41.7
Iowa34
Kansas28.9
Kentucky48.9
Louisiana60.1
Maine42.2
Maryland44.5
Massachusetts47.7
Michigan32.8
Minnesota27.3
Mississippi59
Missouri42.2
Montana15.3
Nebraska23.6
Nevada9.5
New Hampshire43.4
New Jersey47.1
New Mexico14.6
New York50.3
North Carolina17.8
North Dakota17.8
Ohio39.1
Oklahoma36.5
Oregon27.4
Pennsylvania42.9
Rhode Island47.9
South Carolina49.8
South Dakota20.1
Tennessee54.2
Texas28.9
Utah12.2
Vermont42.7
Virginia44.3
Washington38.4
West Virginia45.2
Wisconsin32.6
Wyoming12.9
Source: Rainwater Harvest Calculator

How to Capture Rainwater for Gardening

Capture Rainwater for Gardening
rain barrel

There are three primary features of capturing rainwater for gardening:

Collection Area

This is the area that includes rainwater that has not seemed into the ground as yet. Any place where you notice dripping rainwater can be used as a collection area. The most accessible location where an immense amount of runoff can be collected is the roof of your house.

Using the calculation method mentioned above, you can determine how much water your garden needs and if your roof is capable of collecting the same, if not more, quantity. If you have two downspouts, each of the spaces serves as collection areas for rainwater. And hence, the more barrels you have, the more rainwater you will be able to capture.

Transportation System

The gutters act as transportation systems, along with the edges of your roof. They are the primary method and way water reaches your plants or the barrels for storage facilities. The gutters and downspouts can be made using aluminum or plastic.

The size of these systems is of incredible importance since they need to be large enough to carry a significant amount of water. Most homes have gutters that 5 or 6 inches wide, and that is enough to carry 1000 square feet of water. If the roof is larger, they should have larger gutters for sufficient collection and transport.

It is also recommended to include filters in your roof gutters and downspouts. This helps to prevent leaves or any other debris from clogging them and hindering the transportation system.

Storage Unit

While the steps mentioned above are important, the storage facility you install is the primary step in installing your rainwater collection system. There are many types and sizes of barrels available, and each of them works as great water storage units. If you decide to make a barrel or buy them, they need to placed in the appropriate place.

Locate and place the barrel under the downspout that is also close to your garden. Dig out a 4-inch deep area that is the same dimensions of a cinder block and fill the hole with pea gravel. This ensures the base is strong enough to level the cinder blocks and drain away water to keep your foundation dry. The higher your barrels, the better because that helps to get the spigot off the ground.

The size of your barrel depends on how much water you are willing to store. Three standard 55-gallon drums store 165 gallons of water that are ready for use in your garden. The more water you can store, the better. Pipes can also be attached to each barrel, so they are linked together, and the capacity of your overall system increases.

To avoid overflowing water in your storage units, you can install an overflow port near the top of the water and attach a hose to divert excess water elsewhere. The cinder blocks placed on the bottom also help to keep your foundation dry.

DIY Rainwater Collection Systems

If you are feeling innovative, there are many other ways to capture rainwater for gardening. From basic to advance systems, here are details of a few of them:

Small Collection Facility

If you are collecting rainwater for only a few flowers or a small garden, this collection facility is ideal for that. It only requires a basic garbage can and a few tools to capture rainwater. Such facilities are purely DIY and save substantial costs. They also filter large debris for an efficient system.

PVC Rain Barrel

Materials such as PVC are sturdy and large enough to transport rainwater. They are also cost-effective as the barrels can be bought from a local recycler or car washes. Hence, you only need to purchase the pipes for transportation purposes.

275 Gallon Rainwater Collection

This system is based on the industrial 275-gallon container known as an IBC. Evidently more large-scale and meant for big gardens, this water catchment system collects five times more water than a regular barrel. You can opt to buy the large gallon, or create your own – both ways work as ideal storage and collection units.

Filtered Trashcan Barrel

Moving one step further when collecting water, filters can also be added to storage units to prevent any sort of debris from accumulating in the water. In this rainwater collection system, a filter sheet is placed on top of the barrel for a budget-friendly alternative. It prevents clogging and allows water to pass through the spigot with ease as well.

Galvanized Stock Tank

You can also convert a galvanized stock tank into a rain barrel. With its rustic look, it not only works as a great storage unit but also adds an aesthetic look to your rainwater collection system.

Due to his hard material, installing pipes and connecting the gutters to this tank may be tricky. However, if you are an expert in carpentry or basic engineering, this process will suit you well!

Fencewell Water Tank

Fencewell is a rainwater tank made up of several pipes stacked up to create a fence. The primary purpose is that instead of a water tank taking up additional space in your backyard, the fencewell can act as a boundary of the property and save fence costs.

The system can be built on slopes, and separate sections can be utilized for different water uses as well. Hence, by saving space and adding modularity to the system, one can create a sufficient rainwater collection facility.

Benefits of Capturing Rainwater for Gardening

  1. Helps the environment. For starters, collecting rainwater benefits the environment in a number of ways. It can reduce the risks of erosion around downspouts in the garden and control storm-water runoff. Furthermore, rainwater also does not produce scale and corrosion compared to hard water. Hence, all metal-based materials will remain protected, as well.
  2. Diminishes demand on groundwater. Digging wells is not only an expensive task, but it can also damage the soil in areas where the ground is dug up for water. By collecting and storing rainwater, they can be used during times of drought and also help maintain soil health.
  3. Utilization for multiple purposes. Without a doubt, rainwater collection facilities provide water for your flowers and plants. The same water can also be utilized for washing clothes, dishes, and sanitation purposes. All that is essentially required is an appropriate filtration process for the water to be sufficient for use.
  4. Improves plant growth. Using rainwater can flush the soil buildup created from various plants and underground soil. Since rainwater is free from harmful pollutants and contaminations, they may also contain tons of nutrients your plants require.
  5. Contains acidic substances. Experts are aware that organically grown plants prefer soil pH levels between 5.5 and 6.5. Rainwater is the exact pH range required and hence, helps the plants to balance their pH levels sufficiently.
  6. Contains nitrates. Rainwater also contains nitrates – one of the three macronutrients needed for plants to develop lush foliage. Many forms of nitrogen cannot be absorbed by plants. Nitrates, on the other hand, which are made up of nitrogen and oxygen are consumed by plants easily through the soil. Without rainwater, the soil would not be able to store sufficient nitrate compounds for plants to thrive.

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The Key Takeaway

How large you’d like your rainwater collection facility to depend on you. Additionally, how much you’d like to invest in the system is dependent on you as well. By calculating your costs, garden size, and area’s precipitation levels, adopt the methodologies mentioned above, and learn how to capture rainwater for gardening. As we move to an eco-friendly world, this system is also ideal for those who are looking to save the world from its depleting resources. Utilize rainwater efficiently and watch as your plants grow more luscious than before.

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