Introduction: Rainwater Harvesting System

This instructable is partially incomplete as it is a work in progress and is being documented as is it created to prevent information being lost. This is a small part of a much larger project so it will only be focusing on the catchment part of the system with other better documented instructables to come (portable solar generator/pump system, Berkey water filtration system, and more). This project is being done with limited funds by utilizing as many recycled materials as possible. It will be upgraded to a more efficient version over time.

The goal of this tutorial is to create an efficient rainwater catchment system. This achieved by diverting the rainwater from a gutter system into a reseviour tank. Steps will be discussed to replicate the system created and insight/lessons learned will be included for the reader to better apply techniques. References will be included for further research of uncommonly known information.

Quick Disclaimer

Before starting this tutorial, check with local laws to ensure that a rainwater catchment system is not regulated. In order to create this system, modifications to the gutter spouting will have to be made. Rentin tenants and persons belonging to a HOA (homeowners association) should acquire permission in advance to modify the existing system. Some minor usage of tools is required. Always make sure caution is used when operating all equipment. Many steps in this tutorial are dependent on another. Creating a well thought out plan in advance is highly recommended. The author takes no responsibility for any repercussions or injuries incurred from following this tutorial.

Step 1: Tools and Materials


  • Jig saw / hand saw
  • Screw driver
  • # 10 Hex driver
  • Crescent (adjustable) wrench


Comprehensive list in the works as some parts have been changed for better efficiency. All listed materials were purchased from Lowes.

Step 3

  • (8) Cinder blocks
  • (4) 2x4 weather treated

Step 4

Being Modified-post on next edit

  • HILLMAN 123072 self tapping metal screws

Step 5.A

  • Brasscraft HU22-12MHX P Male Hose Union
  • Brasscraft HU21-8-12X P Female Hose Adapter (MIP End)
  • DANCO 88009 Faucet Locknut
  • HILLMAN 491419 3/4" Flat Washer

Step 5.B

Being Modified-post on next edit

Step 5.C

Being Modified-post on next edit

Step 6

  • 5/8" garden hose (double female ends)

Step 2: Survey Your Location and Current System to Determine Best Location.

The captured water will be used short term for watering the garden, but is intended ultimately in the event of a disaster or lack of working water mains. This factor played a huge part in the chosen location. In the event of a catastrophe, a person would not want to advertise to the world that they are the only one with water. In this project, the largest surface area of the roof runs to the corner of the house furthest from the garden. This requires routing the water back toward the cellar entrance where the tank is placed. A future project will detail the solar-powered marine pump system used to lift the water to the garden area.

Step 3: Prepare You Chosen Location for Catchment Tank.

Most systems will require the ground to be prepared to support the weight of the tank at this point. Luckily, the tank in this project sits on a concrete surface. However, a simple riser is used to allow for easier access to the output port on the 300-gallon IBC tank (, 2015). This was created by placing groups of two cinder blocks at each corner of the riser and two double stacked 2x4s to help support the middle weight. The tank is placed directly on top of the boards.

Step 4: Modify Gutter for Rain Diversion.

There are many diverter system that can be purchased for different gutter types. The materials used in this build were all recycled pieces from various other projects. The diverter consist of 3x4 spouting, 5/8" coupling with rubber grommet inside, 5/8" male to female elbow (needed to redirect flow around corner), 5/8" double male coupling for the hose, 3" bolt, 3 washers, 4 nuts, a small piece of wood (the handle), part of a 5-gallon bucket, and two-part epoxy. The diverter "flap" was made by cutting a piece of the 5-gallon bucket and heating it to fold over the bolt. Two part epoxy was then added to secure plastic to bolt. The wood was then added onto the end of the bolt to create a handle.

EDIT: The previous method was not explained in detail as it was not tested at the time of writing. After placing the homemade diverter on the crimped end of the gutter, the internal diverting flap no longer has full range. A new system in the design phase using PVC pipe, a ball vavle, and a Wye (Y) pipe.

Step 5: Modify Tank for Rainwater (incoming/overflow/output)

This step is comprised of three different modifications to the reservoir tank.


This part will be modified in the future to allow greater flow and prevent excess pressure with the use of a one-way check valve . Currently the tank lid has a 5/8" double male coupling to allow a hose to be attached for incoming water.


Most systems have an overflow built into the tank to prevent water backup. The current system is diverted by hand at the gutter and does not have one incorporated. Directly in front of the tank output, there is a drain that runs into the sump pump to remove any spilled water.


As of now, the 300-gallon IBC tank has a 2" nozzle for the drain. Multiple adapters are required to convert from 2" male buttress thread (common type of threading for IBC tanks) to 5/8" male NPT (national pipe thread/standard hose thread) for a garden hose. In the future, the system will have a 2" Y fitting to allow fast local output and diversion for the garden hose pump system.IMAGES TO COME IN NEXT EDIT

Step 6: Create Path From Gutter to Tank.

The water is currently being diverted from the gutter to the tank via a 5/8" garden hose. This will later be upgraded to a 2" PVC pipe to allow better flow of water. It is important to make sure the origin of the water from the gutter is higher than the input port on the tank for the water to flow properly.


As previously stated, this is a long term multi-phased project. The current goal is to get a "working" system in order and modify for efficiency over time. Many modifications have already been made as the learning process continues. The point can not be stressed enough to pre-plan the rainwater harvesting system as much as possible. All comments and input are welcome!!

Step 8: References (2015). Buttress Inch Screw Threads Dimensions. Retrieved from (2015).USED 275 gallon / 300 gallon IBC Totes. Retrieved from