How to Install a Rainwater Harvesting System at Home

Update - May 2020

The decision to get a rainwater harvesting system for your home is a complicated one. However, if done correctly, it can easily be one of the best things you’ve done for your household, saving you money on  your utility bills and allowing you to make the most of the rainfall in your area.

Do you know how to install a rainwater harvesting system at home? With lots of different systems to choose from as well as many DYI rainwater harvesting solutions, there’s no one way to go about it. Still, whatever type of system you’ve chosen to go with, the main principles you should follow look something like this.

Rain water harvesting tank

Step-by-step guide for installing a rainwater harvesting system at your home

Here we’ll talk mostly about larger and professionally-made rainwater harvesting systems and their installation. If you’re looking for a simpler and cheaper DIY solution, here’s a useful guide you might be interested in.

With the bigger harvesting systems, however, you’ll need to not only employ some professional help both from the manufacturer and from a plumber, but you’ll also need to do a bit of planning yourself

1. Plan out everything

The first things to consider are as follows:

  • What type of rainwater harvesting system do you want for your home?
  • What size do you want the main water tank to be?
  • Consider if you want additional water tanks with the main one, and if so, how many of them do you need and where do you need them? Some of the auxiliary water tanks you might want to consider include:
  • A smaller water tank for unfiltered rainwater above the main tank
  • An indoor water tank for the filtered water you’ve pumped from the main tank into your home
  • An overflow tank below the main tank in case of stormwater overflow
  • An enclosed rainwater “catchment area” on your roof, and others
  • Where do you want the tank to be located? Depending on the water harvesting system you choose, the tank can be on your roof, on the ground, semi-buried in the ground (placing the water tank below your home’s deck is often a great idea if possible), or deep underground.
  • Do you want your rainwater harvesting system to be connected to the water mains? If yes, you can refill your water tank with mains water if need be. Alternatively, you can keep the two separate.
  • How will you set up the pipework? The drainpipes should connect in one pipe before connecting with the water tank from a single entry point. How exactly you do that, however, depends on your home’s layout and your preferences.
  • What kinds of water filters do you want? This depends on what you’re going to use the water for. Only gardening? A hot water heating system? Kitchen appliances and showers? Drinking? Each purpose requires different filtration systems.
  • How about the pumps? Depending on what water outlets you need and where you need them you may either need several different pumps or none at all. If you’re collecting rainwater for your garden needs only, it’s most efficient to set up your system in such a way that it works solely on gravity. If you need your system to supply water to your bathroom, however, you’ll need quite an intricate pumping system.

2. Prepare the area for the water tank’s installation

For larger buried or semi-buried tanks, you’ll often need a crane to help you dig the right hole. Check with the tank retailer whether they are offering a crane and what it costs. Some retailers offer free crane installs for tanks above a certain size.

If you want an in-ground water tank, we’d recommend a shallow semi-buried tank. This makes the tank easier to clean and maintain. Ideally, a third of the tank will be above ground, with the rest below. Deeply buried tanks can sometimes “pop out” if they are empty and the water table rises. To avoid this you can also install a drain system with a sump around the buried tank and a water pump.

3. Install the main water tank

With the site prepared, install the water tank. This is arguably the trickiest and most important part of the process, so make sure everything is in order. There are at least three main types of rainwater tanks to choose from, which are:

  • Cylindrical tanks – These are the traditional round tanks, made typically of either plastic or galvanized iron
  • Rectangular tanks – These are narrow and more space-saving, but can be more expensive and have lower capacities
  • Collapsible bladder systems – These can fit in many areas especially in out of the way sections like under the deck

4. Install all the auxiliary water tanks for the harvesting system

With the main tank in place, install all additional water tanks one by one and make sure everything is connected and secured properly.

5. Install and connect all pipework, pumps, and filters

Rainwater harvesting system explained

One possible way to install a rainwater harvesting system

Next come the pipes, filters, and pumps. How and where those go depends on your particular harvesting system. As we said, the drainpipes should typically enter the water tank from a single entry point. Additionally, the main filtration system should be before the water tank too, although the filters can be divided into two separate systems – one before the water tank and one after it. As far as the pumps are concerned, their placement also depends on the specifics of the system and your needs – they can be both before and after the main water tank.

6. Install the water collection and drainpipe systems

Rainwater harvesting systems typically collect water from your home’s roof. You can simply use the drainpipes of your home and redirect them to your home or you can remake your entire roof and turn it into a more effective water-collecting basin of sorts.

7. Connect the system to the mains water supply as a back up (if you want)

Having a rainwater harvesting system doesn’t mean that you won’t need to be connected to the water mains anymore. With the ever-increasing water droughts we’re experiencing, having a back-up is crucial.

Whether you connect the water mains to your water tank or not depends on you, however. Connecting them can allow you to refill the water tank if it gets empty. This can help for the maintenance of the water harvesting system, however, doing so also requires compliance with some pretty strict governmental regulations, like the ones outlined here.

The intention of these regulations is to prevent residential water harvesting systems from leaking contaminated water back into the water mains. So, if you want to connect your system to the water mains, you’ll need a licensed plumber to install the connection. If you want to keep the two systems separate, however, there’s no need to adhere to such regulations.

And that’s about it! Once all the pipes, pumps, filters, connections, and outlets are installed, as well as all the drainpipes and water-catching mechanisms on the roof are properly made and connected to the water tank, everything should be in order.

Some Important Points to Consider

If you plan on using  your rainwater for drinking, make sure you’ve put in an effective water filtration system to ensure that the water you’re drinking is free of biological, chemical, physical and radiological contaminants. We discuss the pros and cons of drinking rainwater here, as well as how to make it safe to consume

If you’re using the rainwater for showering, consider the issues of pressure. Mains water typically has much stronger pressure than water coming from a pump. Additionally, the pressure from the mains water can stop the water from the storage tank coming through.

Always calculate the amount of rain you get in your area and the size of your roof catchment area. The rainfall you receive and your ability to collect it may not match your water consumption and you may not be able to fill large tanks. Before you buy your tank, calculate these by checking the rainfall gauge for your area.

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