Depending on where you are in the world, you will get more, or less rain than other areas. If you are in an area that gets a lot of rain, and even better, if that rain is all year round, then a rain barrel system, as opposed to huge collection tanks, could work marvellously for you.

Living in Johannesburg, South Africa myself, where the rain fall is only in summer, we opted to put in two 5,000 litre tanks to collect the rain during the rainy season and store it throughout the rest of the year. We are finding that it is maybe not enough for our needs as we use the rainwater collected to fill the pool and run through the irrigation system. The one thing you may find if you are about to install a rainwater harvesting system is that you don’t quite realise how much water certain things take. To just top up our pool takes about 2,500 litres, one half of a tank.

This is where the rain barrel system makes so much sense because as you will see below, you can extend it.

Small to Large

No matter your need, there is a solution for you. Even if you just want to collect enough water to drink for the day, you can use a small rain saucer in a bottle. Great for when you get stranded in a rain forest. Hasn’t happened to me yet, but who knows, I might get lost in the Amazon, at least I’ll have water.

Then we have the rain barrel. A typical rain barrel will hold about 50 gallons, or 190 litres of rainwater, which isn’t too shabby. If you then add more rain barrels as discussed below, you can extend that collection amount quite considerably. Put five barrels together and you are looking at 250 gallons or 950 litres, all from a few barrels running down the side of your house and collecting from one point.

The Rain Barrel Manifold System

The manifold system, also called daisy chaining, is where things get interesting. This is how you extend your rainwater harvesting efforts when you find you just need more.

When planning your collection system, make sure you plan for a possible future. If you place one rainwater barrel in a location where you just can’t add more, then you are shooting yourself in the foot. But if you place it on the side of the house where you can add more next to each other, then you can extend your efforts greatly.

The system is quite simple. One barrel acts as the intake, and piping feeds the overflow through to each consecutive barrel. When you add a second barrel you then add piping to the top of the barrel, so as the first barrel fills and starts to overflow, it will overflow into the next barrel, so on and so forth.

There will also be an outlet tap on the first barrel. With each barrel you add, you can either add a new tap to each of the barrels or extend piping at the base with one tap feeding from all of the barrels. The latter option is usually the best plan because as the rain feeds into the first barrel, all barrels will fill equally, and also empty equally so you aren’t left with stagnant water in any one barrel. All you have to make sure of is that you have an overflow pipe at the top of each barrel, or if you have piping at the top of the barrels, which you should anyway, just one overflow from the last barrel in the sequence.

Inlet Methods

The only other thing left to figure out is how to get the rainwater into the first barrel. This largely depending on where you are placing the barrel and where it will be collecting from. If you are placing it at the side of your house to collect from the roof, then you can alter the downpipe from the gutter to flow straight into the barrel.

Alternatively if you are collecting away from the house, you can use a rain saucer, and again, you can daisy chain multiple barrels together. If you are daisy chaining, you could even add multiple rain saucers that are also daisy chained. The system is only limited by your space requirements and your imagination.

You will also want to consider a debris screen or lid. There are a number of methods you can use here from filtering debris at the top of the downpipe to a connection at the end of the downpipe, but the best is a lid on the rain barrel because the downpipe is not the only place debris will come from.

If you live in an area with mosquitoes then make sure your screening stops the larvae from coming off the roof. If you aren’t sure about the mosquito screening, you can also use an alternative method such as vegetable oil or mosquito control rings (mosquito dunks) for your rainwater mosquito control.

If you look around for a rain barrel you will find that most of them are already fitted with the necessary attachments for screening and debris removal, so you are all sorted from the get go. You can also find different designs of rain barrels, from plastic barrels that look like wooden vats to terracotta ones that you can grow flowers on top. If you are building your own system, you will need to check out the individual debris filtering attachments, but everything is available to make a fantastic rainwater collection system, so you can’t go wrong.