How to Harvest Rainwater

*PLEASE NOTE: Some areas and regions have extremely strict policies on rain water harvesting or capturing and storing rain water where as other areas and regions it is ILLEGAL to harvest rainwater. PLEASE check with your STATE and LOCAL GOVERNMENT (County/Town) concerning LAWS and REGULATIONS for RAINWATER HARVESTING in your region prior to attempting to set up ANY RAINWATER HARVESTING type systems.

In a previous article I wrote on harvesting rainwater, I discussed the benefits of such a project. In this article I will discuss how to go about collecting rainwater.

There are three methods to harvest rainwater –- using a rain barrel, utilizing a dry system, or creating a wet system.

Rain barrel. (Courtesy: Innovative Water Solutions)

Rain barrel.
(Courtesy: Innovative Water Solutions)

Collecting rainwater using rain barrels is probably the most popular method. Many people are aware of it and it is very easy to set up. All you have to do is install a rain barrel at a gutter downspout. You can use a recycled barrel or you can purchase a new barrel that is specifically made to perform the task.

The advantages to such a system are that it can be set up so easily by just about anyone at any residence. Barrels are readily accessible either at a wide assortment of stores in your area or even on the Internet.

Disadvantages to the system are capacity of the barrel and a barrel can overflow resulting in wasted water. The capacity of a rain barrel is only 50 to 100 gallons.

The Dry System is a variation of the rain barrel method. However, a larger storage container with much more volume is used. It is called a “dry” system because the pipe that collects the water dries after each rain event.

Dry Rainwater Harvesting System. (Courtesy: Innovative Water Solutions)

Dry Rainwater Harvesting System.
(Courtesy: Innovative Water Solutions)

Benefits of such a system include having the ability to store a large amount of water; it’s an ideal set up in regions where rain occurs infrequently in larger storm events; it is inexpensive to create; and it is very easy to maintain.

A disadvantage of the Dry System is that the tank must be placed next to your house.

In the Wet System, collection pipes are located underground and are connected to multiple downspouts that come off different gutters. The rainwater fills the underground pipes and the water rises in the vertical pipes until it spills into a tank. The downspout and the underground collection pipes must have water-tight connections so there is no leakage and the elevation of the tank inlet must be below the lowest gutter on the house.

Wet Rainwater Harvesting System. (Courtesy: Innovative Water Solutions)

Wet Rainwater Harvesting System.
(Courtesy: Innovative Water Solutions)

Benefits to a wet system include the ability to collect from many surfaces, gutters and downspouts and that the tank can be located some distance from your house.

Disadvantages to the wet system is that it is more expensive to implement because you have to lay pipe underground and there must be a significant distance between gutters and the tank inlet.

Creating a Complete Rainwater Harvesting System

When you create a complete overall rainwater harvesting system you are taking advantage of parts of your home including the roof and the gutters. In addition, you are setting up a system that directs water coming off your home into a large container for storage. The system is very efficient and just about maintenance free.


Here is a diagram showing how the system works.

(Courtesy: Innovative Water Solutions)

(Courtesy: Innovative Water Solutions)

1. Collection Surface
2. Collection Gutters
3. Gutter Protection
4. Rain Head Inlet Filter
5. First-Flush Diverter
6. Inlet Screen
7. Collection Cistern
8. Overflow Port
9. Automatic Top-up Mechanism
10. Pump
11. Water Filter
12. Water Level Indicator

Collection tanks or cisterns or rain barrels can be found at Home Depot. Water harvesting systems can be found at Bushman USA and Rain Tank Depot.

Keep in mind that there are advantages and disadvantages to every tank. Different situations require different kinds of tanks. Prepare the location where the tank will be sitting in accordance to the instructions that come with the tank. Tanks when full are extremely heavy. For example, one gallon of water weighs about 8-1/3 pounds.

Other Things to Consider

The system you create may include “flying pipes.” That means that the pipes that are being used to collect water are some distance above the ground. Such a system has a higher efficiency of collection. Exposed flying pipes may be susceptible to damage during heavy storms and could be a source of injury if someone walks into a pipe.

Do not use a translucent tank in your rainwater harvest system. The material allows sunlight in and that can cause the growth of algae inside the pipes. Do not use a clear pipe water level indicator in the system or you may have algae problems.

Finally, a first-flush diverter is included in the system to divert the first of the rainwater that flows off the roof. This first bit of water has a lot of dust and other particles that may get into the collection tank if it is not diverted.

About Robert Janis

Written by Robert Janis for LawnEq - Your specialists for Lawn Mower Parts and Small Engine Parts. We offer genuine premium OEM parts for Land Pride, Toro and many more dependable manufacturers.