Consider where you will place the barrel.  A barrel needs to be placed where it will collect water coming from the roof, usually at a point where there is a gutter downspout.  Many homeowners’ associations and other neighborhood governance organizations may have restrictions as to where a barrel can be placed on the property.  Make sure you have the proper approval for your project.

A full, 55-gallon rain barrel can weigh 400 lbs.  Barrels are typically elevated 12 to 36 inches from the ground to increase water pressure. The barrel must be placed on a firm, level surface to ensure stability.  If small children are a concern, it may be prudent to anchor the barrel to a post or wall to prevent tipping. The following websites show examples of anchored rain barrels.

https://extensionpubs.unl.edu/publication/g2220/html/view

https://www.superiorwi.gov/DocumentCenter/View/457/REASONS-TO-HAVE-A-RAIN-BARREL-AT-HOME?bidId=

Some rain barrels have a wide mouth construction.  Small animals or children could fall into the barrel if the opening is left unsealed. If you choose a wide mouth container, make sure the screening is secure to prevent accidental injury. https://www.aces.edu/blog/topics/fish-water/chapter-4-diy-rain-barrel-construction/

Have a plan for mosquitoes. Standing water is a breeding ground for mosquitoes so make sure all entry points are completely screened or sealed.  You may also place mosquito dunks in the barrel if needed.

Plan for overflow.  A barrel may fill faster than you can use the water.  Once the barrel is full, the excess water needs somewhere to go.  In a simple, open mouth barrel, water may overflow from the top, leading to puddling at the site.  Many rain barrels come with a built-in overflow valve, to which you can attach a hose to divert the water away from the foundation of the house to a more desirable location. You can also add your own overflow outlet to an existing barrel.

Don’t drink the water!  Water from a rain barrel is considered gray water and not potable.  Water flowing down a roof can pick up bacteria from animal feces, and chemicals from shingles and other roofing products. To reduce the risk of contamination from harvested water, some sources recommend keeping water off fruits and foliage of edible plants. https://publications.extension.uconn.edu/2018/05/18/can-i-water-vegetables-with-my-rain-barrel-water/