Cistern Size

Cistern Image

Collecting rainwater is quite simple, and can be quite successful if you follow these steps:

Step 1: Sizing

There are several factors in deciding the appropriate size of your system: 

  • What is the area of your roof?
  • How much space to you have allotted for your rainwater storage?
  • What are your intended purposes for the collected rainwater?

Research the average amount of rainfall in your regional area, to help you determine how much water can be captured.

Step 2: Choosing the Proper System

Choose a collection tank that is suitable for your rainwater harvesting system. 

Cistern Types Benefits
Fiberglass Tanks no rust problem, durable
Polyethylene Tanks affordable, mobile, available in an assortment of sizes and shapes
Plastic Garbage Can affordable, available
Barrels aesthetics, great for small household systems
Steel Drums available, great for small harvesting systems, mobile
Galvanized Tanks affordable, mobile
Concrete Tanks, Stone or Concrete Block durable, permanent

Cisterns sized from miniscule to mammoth gracefully store water captured on site until it is needed for toilets or garden hoses.  Homeowners can put a 50-gallon rain barrel at the end of a downspout, or connect to gutters to an expandable “bladder” under the house. Underground storage tanks are en effective option for larger facilities.  These products have been engineered to be durable, long-lasting and deter mosquitoes and animals.

Step 3: Location of Cistern

When determining the location for your rainwater harvesting tank be sure to place it at a high elevation point, 3 to 4 feet above ground is ideal, making sure that the structure is sturdy.  Be aware that a 55-gallon full tank can weigh up to 500 pounds!

Above Ground Cisterns vs. Below Ground Cisterns 

  • Above Ground Cisterns: require little to no maintenance and are commonly found on residential sites.   One advantage to having cisterns located above ground is the fact that gravity aids in guiding the water throughout the irrigation systems and no additional pumping is necessary.
  • Below Ground Cisterns: are often more expensive than cisterns found above ground and are usually found in colder climates. Below ground cisterns have limited accessibility after they are installed, inhibiting leak repair and other maintenance thus requiring additional structural support to reduce the threat of the cistern floating.  Unlike above ground cisterns, that require little to no pressure, underground cisterns require the use of a pump to obtain water. Underground cisterns do not to be located directly below gutters, which allows more flexibility, and they do not take away from yard space.