What's the difference between a cistern and a rain barrel?

Rain barrels and cisterns perform essentially the same task – capturing and storing rainwater that comes from roof runoff – but the two typically differ in size, installation, and application. Rain barrels are often constructed from a plastic barrel, similar in size to a 55-gallon industrial drum. They feature a partially open top covered with a screen to filter debris and are placed under downspouts to maximize catchment. Cisterns are comparable to rain barrels but are usually larger and located at locations with larger roof areas and thus more runoff. Cisterns can also be buried whereas rain barrels are located above ground.

How do they work?

After collecting runoff, rain barrels and cisterns make the water available for use through a standard spigot located at the bottom of the container. The pressure above allows the water to flow freely through a connected hose to be used for yard irrigation or other non-potable uses. Roof runoff contains contaminants that make the water unsuitable for human/animal consumption. Underground cisterns rely on pumps, adding to their cost, but are able to move water more quickly.

Maintenance typically involves emptying and rinsing the container at the start and end of the rainy season. If the inside is particularly dirty, a few tablespoons of soap and a couple teaspoons of vinegar can be added to the mix. Make sure the seal on the top is tight to keep mosquitoes out, as they are attracted to and breed in standing water. In addition to keeping your rain barrel and cistern clean, it is also necessary to ensure gutters and downspouts are in good condition and free of debris to maximize water collected.

Where do I buy a them?

Rain barrels are definitely more available and easier to find in stores around Los Angeles than cisterns. Home improvement chains such as Lowe’s and Home Depot stock them as well as many garden supply stores. Barrels can also be ordered through online retailers such as Amazon however shipping costs may apply. For more information on where to purchase rain barrels and cisterns, please visit treepeople.org.

What type should I get?

Opaque plastic drums are a popular type of rain barrel for residential use. Home improvement stores also offer containers made of other materials such as ceramic clay, stone, wood, and metal. Plastic barrels are the most cost-effective and lightest, and they also come in the widest variety of sizes and designs. Some have the possibility of deteriorating with high sun exposure, so make sure you get one with adequate UV protection and thickness. Clay and stone barrels are typically used for smaller amounts of rain capture and are bulkier. Wood barrels are more expensive but some prefer their aesthetic over plastic. Finally, metal is mostly used on larger systems like cisterns, though these can also be made of heavy-duty plastic. Metal containers tend to be used for more permanent applications as well. Retailers sell metal rain barrels but many homeowners also use repurposed metal 55-gallon drums instead as a cheaper option. However, it is important to note that homemade systems of any size as well as store-bought barrels with a capacity of less than 50 gallons do not qualify for the rebate.

How much do rain barrels and cisterns cost?

Cost depends mostly on the size of the rain barrel/cistern and its material. The most common type of rain barrel (approximately 50 gallon plastic containers) typically retail for $90-140. Wooden barrels of similar capacity can cost up to $400-500. Larger cisterns are priced up to $1,000 plus installation and pump costs if located underground but hold significantly more water – many from 500 to over 1,000 gallons.

Los Angeles residents can qualify for a $50 rebate per barrel (limit two) and up to a $500 rebate for a cistern (limit one) with a minimum capacity of 200 gallons. Other customers in the Metropolitan Water District's service area can apply for similar rebates starting at $75 and $300, respectively. Details and requirements can be found at socalwatersmart.com.

Tree People of Los Angeles is also offering a program to provide 55 gallon rain barrels from Rain Barrels International for a discounted price of $85, making the barrels free when combined with the LADWP rebate.

Interested in learning more? Sign up for TreePeople's rainwater harvesting workshop.