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Rainwater Harvesting Methods

Learn how to collect rainwater and the products you need

How to Harvest Rainwater?

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So you're convinced that you want to start collecting rainwater at your house. Below you will find the resources to educate yourself on the best method for harvesting rainwater in your situation. You will also find information about the basic components of a rainwater collection system. Even though rainwater catchment is an old technology, there have been many improvements over time through product innovations.

What are the different methods to collect rainwater?

The only thing that differs in the following methods is the scale of the system. They all follow the same principles but differ on aesthetics and actual water conservation effectiveness. Click the pictures for a closer look.

Rain Barrels

Rain barrel to capture a small amount of rainwater

This method is the most common and one that many people are familiar with. This involves installing a barrel at a gutter downspout to collect rainwater. The actual barrel may be a recycled barrel or a new commercially available rain barrel.
Pros:
  • Easily implemented by anyone at any residence
  • Barrels are readily available in your community or at various stores & websites
  • Barrels don't take up much space so they can fit into any situation
Cons:
  • Capacity is generally only 50 to 100 gallons
  • Easily overflows and wastes collection opportunities

"Dry" System

A dry system rainwater collection system where the pipes dry out after a rain event

This method is a variation of a rain barrel set-up, but it involves a larger storage volume. Essentially, the collection pipe "drys" after each rain event since it empties directly into the top of the tank.
Pros:
  • Can store a large amount of rainwater
  • Great for climates where rainfall happens with infrequent, larger storm events
  • Can be inexpensive to implement
  • Less complicated system so maintenance is easier
Cons:
  • The storage tank must be located next to your house

"Wet" System

A wet system rainwater collection system where the pipes stay wet after a rain event

This method involves locating the collection pipes underground in order to connect multiple downspouts from different gutters. The rainwater will fill the underground piping and the water will rise in the vertical pipes until it spills into the tank. The downspouts and underground collection piping must have water-tight connections. The elevation of the tank inlet must be below the lowest gutter on the house.
Pros:
  • The ability to collect from your entire collection surface
  • The ability to collect from multiple gutters and downspouts
  • The tank can be located away from your house
Cons:
  • More expensive to implement due to underground piping
  • Sufficient difference between gutters and tank inlet must be available


How do I create a complete Rainwater Collection System?

The image below shows a complete rainwater collection system. While some of the components shown are absolutely necessary, not all of the components listed are required. Although, all of these components will help create a harvesting system that is highly functional and nearly maintenance-free.

Rainwater collection and harvesting system components

Collection surface for rainwater harvesting

Collection Surface

Collection surface for rainwater harvesting

Collection Cistern

Collection surface for rainwater harvesting

Collection Gutters

Collection surface for rainwater harvesting

Overflow Port

Collection surface for rainwater harvesting

Gutter Protection

Collection surface for rainwater harvesting

Auto-fill / Automatic Top-up Mechanism

Collection surface for rainwater harvesting

Rain Head Inlet Filter

Collection surface for rainwater harvesting

Pump

Collection surface for rainwater harvesting

First-flush Diverter

Collection surface for rainwater harvesting

Water Filter

Collection surface for rainwater harvesting

Inlet Screen

Collection surface for rainwater harvesting

Water Level Indicator


What kinds of rainwater storage tanks can I use?

Well, you can collect rainwater into any storage vessel but here are some of the more popular, commercially available, rainwater collection tanks. Every tank has its' own pros and cons and different situations call for different tanks. One important note to remember is to ensure that your base preparation is performed in accordance to the tank manufacturer's instructions. These rainwater storage tanks will be extremely heavy when water is present inside them. Remember, water weighs 8.34 pounds per gallon!



Some issues to think about when installing a rainwater system

Flying Pipes

Pipes flying through the air to collect rainwater from multiple downspouts

This issue is not necessarily bad as it allows for a higher efficiency of collection, but for most people, they don't want to see PVC pipe flying overhead at their homes. Some other things to think about is the possibility of damage to the collection pipes from storms and injuries to people who could run into the pipes.

Tank material that allows sunlight inside

Translucent tank that exposes rainwater to sunlight and produces algae in the tank

Do not use a translucent plastic tank for rainwater storage! The system may look great right after being installed, but unless you constantly put chlorine bleach into your tank, then the water inside the tank will grow algae and will look like pea soup. Click on the image to see this. These translucent tanks are meant for chemical storage not for raw water storage.

Water level indicator using a clear pipe

Clear pipe used as water level indicator that becomes caked with algae

You find this type of water level indicator promoted on many DIY rainwater collection websites. Well, as in the previous issue with the clear or translucent tank material, the same phenomenon will occur with these clear pipe or clear flexible tubing water level indicators. The water in the indicator pipe is exposed to sunlight which promotes the growth of algae inside the clear pipe. Even if the indicator has a drain valve in it, the water vapor trapped in the clear pipe can still grow algae. Click on the image to see what the clear pipe water level indicator looks like after some time of use.

If you install a water level indicator on your rainwater storage tank, make sure to use a different technique than a clear pipe indicator.

First-flush diverter that mixes with good rainwater

First-flush diverter that doesn't separate first flush from good rainwater

The purpose of a first-flush diverter (as seen in this image) is to divert the first bit of rainwater that drains from your collection surface. This first bit of rainwater has the highest concentration of dust and other particles. The diverter shown in this image is normally called a "poor man's diverter". As you can see though, the initial flush of water that has filled the pea-trap shaped pipes just pushes into the collection tank. In this configuration, you get no benefit... you might as well connect the downspout pipe straight to the tank inlet.

How can Innovative Water Solutions help me out?

Find out about our Rainwater Collection System Installation Services.


Click here to schedule a Rainwater harvesting system consultation


 
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