Rain Barrel Mosquito Mitigation and Elimination

Rain Barrel Mosquito Mitigation / Elimination – District Garden

Recently a customer asked us to put together a document to bring to their condo board about mosquito mitigation in our typical rain barrel installation. So, we thought, why not share that information with the good folks in Washington DC, Maryland and Virginia.

Below find the contents of the PDF on how District Garden’s installs prevent mosquito breeding and our recommendations on mosquito mitigation / elimination in your rain barrel or cistern system.


Many of the concerns about mosquitoes and rain barrels are valid. However, there are a number of easy and low or no maintenance solutions for them. Our typical installation circumvents all general mosquito concerns. We use an inline diverter and a closed system which will be illustrated below. We also illustrate a setup (that we do not use) that is more prone to mosquito breeding. Further, we offer advice on further low cost preventative steps one can take to mitigate mosquito concerns in their current or future rain barrel / cistern setup. Basically, here’s how we reduce and removal the threat of mosquito breeding in your rain barrel system.


Our Typical Installation

Rain Barrel Installation

Rain Barrel Example

Above is an actual photo and a drawing of a linked barrel system that we do install on a regular (700+ since 2011) basis. Note that the diverter connects to the downspout and then to a compression style fitting in the side of the barrel itself. The tops of the barrels are sealed closed and have two access plugs. Mosquitoes simply cannot get into the system easily. Water that might collect on top has two small drilled holes in the lip to drain out, but would dry before a week passed regardless. This setup also prevents backup of the gutters when the rain barrels are full as the water will simply continue down the downspout. In this style of rain barrel mosquito control is more easily handled.


Old-Fashioned / Mosquito Prone Installation

Open Top Type Install Rain Barrel

Open Top Type Install

Essentially, even with some light screening this “open style” installation would be prone to mosquito breeding. If the water was left standing for a period of time greater than one week breeding can occur. Ignoring the fact that the overflow here is too small for the application and could cause backups in the guttering, this is not the setup to go with to avoid mosquitoes since one cannot guarantee how often the water will be used.


Further Mosquito Mitigation (If Desired)

It  is certainly possible to do any of the following things to further mitigate the chance of mosquito breeding in your rain barrel system.

  • Cooking Oil: Adding ¼ cup of cooking oil to each barrel is an organic way to prevent mosquitoes from breeding as it would suffocate any larvae on the surface of the water.
  • Bleach: 2 ounces of bleach per barrel is EPA drinking water guidelines safe, and therefore is perfectly acceptable for plant water.
  • Mosquito Dunks: Typically commercially available (Amazon, etc.) at around $1 per dunk. They treat the water for 1-2 months in your average rain barrel.


Due to the fact that we use a closed system in the vast majority of our rain barrel and cistern installations, mosquito breeding concerns are essentially non-existent. For those wishing to go further, any of the steps above will work well.

Feel free to contact us with additional questions.