How to Effectively Harvest Rainwater with Barrels

How to Effectively Harvest Rainwater with Barrels

Every time the skies open with heavenly rain, money is washing down the drain. Creating a rainwater collection and storage system with barrels is simple.  You just need to make sure you choose the best rain barrels. Every time you collect water, you are replacing chemically treated and costly city water, which is better for your garden and your wallet.

The three parts of any rainwater harvesting system are the collection area, the transport system, and the storage. Let’s look at how you can efficiently harvest rainwater with barrels.

Collection Area

You can collect rain from anywhere that it doesn’t soak into the ground, but it is most common to use your roof as the collection area due to its large surface area.

Working out how much water you can collect from your roof involves complex calculations. However, it is safe to say that an average two or three bedroom home with a 25 x 40-foot roof has a sufficient roof area to collect enough rainwater to water your garden, and you will be able to harvest around 600 gallons of rain per hour in moderate rainfall. The barrels you have connected to the down-pipes from your roof, the more water you will collect.

Transport System

Your gutters and downpipes along your roof’s edge are the transport system for your rainwater.

Material: Aluminum or plastic are the two most common materials for gutters and downpipes. The size of the pipe is important, but the material is vital.

Size: Your gutters and downpipes need to be large enough that they can carry the water from the roof. Most gutters are around 5 inches wide with 3-inch downpipes, or 6 inches wide and their downpipes are 4 inches wide.

For roofs with a 1,000 square foot area, a 5 inch gutter with a 3-inch downpipe is large enough. If your roof is larger than this, ensure that you have bigger gutters and downpipes.

Filter: Make sure that your gutters have a mesh screen at the top of the downpipe so that leaves and debris down end up clogging your downpipes. If you live in an area where mosquitoes are a problem, use fine aluminum mesh to keep insect out of your water barrel.


The storage system you use for your rainwater collection is the heart of the process. The barrels will be used for storing water to use throughout dry months.

Where you place your barrels is very important. They need to be placed under your downpipes near the areas that you are going to water with the collected rainwater. Your barrels need to be placed on a solid base that is raised off the ground. It is best to use cinder blocks as they are easy to get and move.

Dig a 4-inch-deep space that is the length and width of the base you want to create. Cover the base with ¼ inch gravel. This allows you to drain away excess water and keep the foundation dry. The higher you build your foundations, the better the pressure will be from the barrels. You need to ensure that it is high enough that you can get your watering can under the tap.

You also need to carefully consider the capacity of the barrels your install. You can only store as much water as your barrels can hold. It is recommended that you install at least three 55 gallon barrels in you have an average sized garden, increasing the number based on the amount you need for the dry season.

If you have space in your yard, save as much rainwater as you can. If you find that you have water left after the dry season, you can still use it in the wetter season to supplement the rain, allowing you to water your garden to your heart’s content without having the cost of using city water.

Water is one of the most valuable resources on the planet – more so even than gold and platinum. Without it, humans, animals, and plants cannot survive. By harvesting rainwater, you are taking pressure off the city’s system, and using the earth’s gifts to the fullest.