How to Harvest RainWater for Off Grid Living: A Step-by-Step Guide

Everything You've Asked About Rainwater Harvesting Off Grid And More!

A Step-by-Step Guide To Designing & Building Your Own Water Harvesting System.

The Off Grid Cabin Water Harvest

Water is one of the most essential resources for human survival, but it can also be one of the most expensive and scarce ones, especially for those who live off the grid. If you are looking for a way to reduce your water bills, conserve water, and become more self-reliant, then harvesting rainwater might be the solution for you. We’ve built our own rainwater harvesting system that includes a “first flush” component which serves to automatically clean our roof from contaminants at the beginning of every water collecting event.

So what is rain water harvesting? It’s the practice of collecting and storing rainwater that falls on your roof or other surfaces, and using it for various purposes, such as drinking, cooking, washing, gardening, and more. It is a simple, sustainable, and cost-effective way to provide free water for your off-grid home. You can also use the collected rainwater to supplement any drinking water you’ve brought or bought for your off grid home. You aren’t forced to drink it even though it can be easily and cheaply filtered to make it drinkable.

In the following blog post, I’ll show you how to harvest rainwater for off-grid living in four easy steps.

  1. How to choose a suitable location and method for collecting rainwater
  2. How to install a storage tank or barrel to store the collected rainwater including building a “first flush” system
  3. How to add a pump and a filtration system to pressurize and filter the rainwater
  4. How to connect the rainwater system to your off-grid home’s water supply

NOTE: This serves as a reference solely. Be sure to research and adhere to the rules, regulations and laws in your area. 

By following this step-by-step guide, you will be able to enjoy the benefits of harvesting rainwater for off-grid living, such as saving money, reducing your environmental impact, and becoming more independent. So, let’s get started!

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Step 1 Choose a suitable location and method for collecting rainwater

One of the first steps to harvest rainwater for off-grid living is to choose a suitable location and method for collecting rainwater. This will depend on several factors, such as the type of catchment you want, the amount of rainfall in your area, the size and type of your roof, the space and budget you have, and the legal regulations in your state/province/country. Find the Canadian Rainwater harvesting regulations here.

The most common and effective way to collect rainwater is by using your own gutters, which then collect the rainwater in rainwater barrels or plastic tanks. This method allows you to capture large volumes of water from your roof, which is usually the largest catchment area in your property and store it for later use.

Rain Water Harvesting

You can also store water in an underground cistern.  We also make use of a first flush system to divert the first dirty water that comes from off the roof. This helps to significantly improve the quality of the water you collect.

If you do not have the option to collect rainwater from the roof, or if you want to increase your water supply, you can use other methods, such as using a large tarp placed on the ground, which then channels all the water into a barrel or cistern. This method is simple and cheap, but it requires a lot of space and maintenance. You can also use other catchment areas, such as patios, driveways, or green roofs, to collect rainwater.

water harvest fish

Another important factor to consider is the total storage capacity of your rainwater collection system. You’ll need a large enough tank/barrel or multiple tanks/barrels to store the collected rainwater for later use during extended dry spells and during cold weather events (winter). We also have a 300 liter (80 gallon) secondary water container in our loft that stays at cabin temperature all year long. We can easily fill this horizontal water tank with a small portable electric pump or even a small cordless drill pump. The size of your tank or barrel will depend on how much water you wish to have on hand, how often it rains in your area, and how much space you have to store your rain water.

We use a small electric pump to transfer potable drinking water from a couple of 5-gallon water jugs up to the water storage tank in the loft using a drinking water safe Flexilla garden hose reserved just for this evolution.

portable electric water pump

The Off Grid Cabin Loft Water Tank

Our loft tank, in the bottom left of the above photo, holds 80 gallons (300 liters) of drinking water. There is a triangular shaped tank that we are looking to purchase to further increase the floor space. Since the loft has 45 degree ceilings we have a lot of storage space along the bottom edge.

By choosing a suitable location and method for collecting rainwater for off-grid living, you will be able to maximize your water resources and reduce your dependence on external water sources.

Underground rain water storage tanks



We may consider something like this in the future. For now we get enough rain, often enough here in Nova Scotia, that we’ve never been without water. Also, we live 60 feet from a fresh water lake and since we’re not drinking the water we can always pump it from the lake to use as shower water.

Step 2 How to install a storage tank or barrel to store the collected rainwater

1 Gather Your Materials

Before you begin, make sure you have all the necessary materials and tools on hand such as…

Rainwater storage tank or barrel
Concrete blocks or a stable platform
Gutter system and downspout
First flush diverter (optional)
Overflow system
Pipe and connectors (if needed)
Prescreen or filter (for keeping debris out of the barrels)
Garden hose or pipes
T-connectors and clamps
Post barrel filter (for keeping debris out of the pump)

2 Choose the Right Location

Select a suitable location for your rainwater storage tank or barrel. It should be close to the area where you plan to use the harvested water and near your gutter downspout. Ensure the ground is level and stable to support the weight of a full tank. 55 gallons of water weigh 460 pounds. We placed our barrels on cinder blocks as we have two water barrels that are connected.