Rainwater Harvesting

Rain Barrels and cisterns are a cost-effective way to capture rain water and reuse it to water your landscape. Capturing rainwater also reduces storm water discharges. Water that normally would have run into the storm drains and out to the ocean, is now being redirected into a system that allows you to return it to the soil and recharge the groundwater.

A cistern, essentially a larger form of a rain barrel, is a rainwater harvesting system for storing water, usually underground. It captures non-potable water run-off for the purposes of reusing the water for watering gardens.

Grey rain barrel with flowers on top.

Where to Get a Rain Barrel

Rain barrels are often available at gardening and hardware retail establishments, including:

  • Rain Barrels Intl.
    (919) 602-6316
  • Southeast Construction Products
    1239 S. Myrtle Ave.
    Monrovia , California
    (626) 359-9367

How to Install a Rain Barrel

  1. Find the best place to put your barrel.  Look for places where downspouts lead to hardscape areas and where overflow can be diverted from foundations and used on a garden area.
  2. Raise the barrel about 10-15". You may want to place the rain barrel on concrete blocks if you are going to use a hose to direct water to your garden or if you want to fill up a watering can from the spigot.
  3. Decide how to best reconfigure the downspout. It will likely need to be shortened and have pieces/elbows added.
  4. Cut the spout at the desired mark with a hacksaw.
  5. Attach the elbow(s) over downspout. Use needle-nose pliers to crimp the ends of the cut downspout and slide it inside the elbow. Attach the elbow to the downspout with screws, or for added stability, consider securing the elbow to the building with a bracket.
  6. Conduct a test run. Use a water hose to flow water through gutters and into the rain barrel. Make any needed changes.
  7. Secure the rain barrel with metal/all-weather earthquake straps. Use anchors and screws to secure to side of house/building.

How to Maintain a Rain Barrel

  • Empty rain barrels completely. Use wet/dry vacuum or empty any water into the garden.
    If there is any build-up of organic matter, spray out with a hose.
  • Check earthquake straps and footing to ensure they are secure. Repair any holes in the mosquito screen and/or replace filters as needed.
  • Check for leaks in the barrel, valves and overflow to make sure they are working properly. Repair as needed.
  • Inspect overflow area to make sure that water will continue to drain away from structures and does not flow onto pavement or neighboring properties.
  • Once your rain barrel is installed, maintenance is easy. Simply use the collected water and make sure that the rain barrel is emptied on a regular basis. Right before a big storm, double check that the rain barrel is ready to go.


What are the benefits to using rain barrels?

  • Naturally softens water with no additives, and is better for your plants.
  • Lowers your water bill.
  • Decreases wastewater and the corresponding energy consumption used to treat wastewater.
  • Reduces water pollution in our rivers and lakes by reducing storm water runoff.
  • Rain barrel-gathered water is not subject to community watering restrictions.

Why is storm water bad for rivers, lakes and other natural bodies of water?

Water that falls directly from the sky into lakes is not the problem—it is the storm water that runs over impervious surfaces and ends up flowing in fast, hot and dirty. It can pick up pet and livestock waste, fertilizers, pesticides, detergents, trash, invasive plant seeds, automotive liquids like motor oil, antifreeze, brake fluid, leaves, grass clippings and more. All of these elements have detrimental effects on the quality of the water in lakes, rivers, streams and our oceans.

Rain barrels can help you have a direct impact on all these issues by temporarily holding water back from discharging into our storm drains. In nature, this delay occurs because rainwater soaks into the ground instead of running across pavement. Obviously we can’t remove our houses and streets, so we use rain barrels and rain gardens to replicate this delay.

My roof is pretty small-is it even worth me getting a rain barrel?

Generally speaking, yes. One inch of rain on a 1,000 square-foot roof will generate about 600 gallons of runoff. As an example, your two-story home is 1,600 square feet of total living space with a roof area of 800 square feet. You have two roof drains, each collecting water from 400 square feet. For one roof drain, you only need two (2) 60-gallon rain barrels to capture approximately 0.5 inches of rain.

Can I drink the water from my rain barrel?

No. Do not drink the collected rain water. The collected rain water is not potable water and should never be used for drinking, cooking, bathing, or washing purposes. The collected rain water should only be used to irrigate your property’s plants, garden or yard.

Can I use the captured rainwater in my vegetable garden?

Yes, but only in the same way that other non-potable water is used. Avoid using overhead irrigation. It is best to use this water for drip or trickle irrigation. This prevents contamination of edible above the ground plant parts that are hard to clean, especially leafy greens. However, the vegetable is not safe to eat unless it is thoroughly washed using “drinkable” water first. Rain barrel water should not be used close to harvest time to water the vegetable garden and should NEVER be used to wash fruits or vegetables from the garden or orchard prior to consumption.

How do I control mosquitoes in my rain barrel?

Rain barrels should have a tight fitting lid, preferably one that screws on and a mesh screen to prevent mosquitoes from entering. A screen can also be affixed to the spigot to prevent mosquitoes from entering into the barrel.

How do I clean the inside of the rain barrel?

It is recommended washing the barrel when disconnecting it for a dry season. Use an environmentally-friendly solution of 2 tsp. of castile soap + 2 tsp. vinegar or lemon juice per gallon of water for cleaning, swishing the solution around inside the barrel then rinsing the inside of the barrel with a garden hose. A concentrated nozzle spray will work well to remove residue from the inside of the barrel. The water in my barrel has an odor and/or algae growing in it. This is natural if the water sits in your barrel for a while. It's the same thing that happens with some lakes, especially when the weather has been very warm. You can ignore it, use the water faster, or check pond or gardening stores for additives that are safe for your plants.

Are rain barrels allowed by building codes?

Yes, the City of Pasadena does not require a permit for rain barrels.