The Downsides of Rain Barrels and Why They Aren't for Everyone

What are the primary health and safety risks associated with storing harvested rainwater?

Harvested rainwater poses significant risks because it acts as a collection vessel for environmental pathogens and chemical pollutants that accumulate on roof surfaces.

• Salmonella and other enteric bacteria often thrive in stagnant water contaminated by bird or rodent droppings found on shingles.
• Heavy metals like lead or zinc can leach from older metal flashing or galvanized gutters into the collected supply.
• Hydrocarbons from asphalt shingles frequently wash into the barrel, creating a toxic cocktail that is unsafe for vegetable gardens.
• Giardia cysts may persist in the barrel, posing a risk if the water is accidentally ingested during gardening tasks.

How do local regulations and legal restrictions impact the use of residential rain barrels?

Yes, legal restrictions often limit usage, such as in Colorado, where strict water rights laws historically prohibited rain harvesting until recent legislative changes. Some homeowners associations also impose bans based on aesthetic concerns, even if state law permits the practice. Always check your local municipal codes before installation.

What maintenance tasks are required to prevent mosquito breeding and bacterial growth in collected water?

To keep water safe, you must physically scrub the interior walls every few months to remove the biofilm layer where bacteria colonies reside. Using a dilute bleach solution—roughly one-eighth cup per gallon of water—effectively sanitizes the plastic, provided you rinse it thoroughly before reconnecting the downspout. Ensure all entry points are sealed with fine-mesh screening to block insects.

A notable nuance involves the use of mosquito dunks containing BTI, a biological larvicide. While these are safe for plants, they lose effectiveness if the barrel frequently overflows during heavy storms, as the active ingredient washes away. If your region experiences high rainfall, you will need to reapply the treatment more often than the standard thirty-day recommendation to maintain control.

How does the size of a roof catchment area limit the volume of water that can be effectively collected?

The catchment volume is strictly limited by the surface area of your roof and the local rainfall depth, with a 1,000-square-foot roof yielding about 620 gallons from just one inch of rain. Many people assume that a larger barrel will solve their water needs, but if your roof footprint is small, even a massive tank will rarely fill during dry summer months. You are ultimately constrained by the sky, not the container.

What are the potential chemical contaminants that may leach into water stored in non-food-grade containers?

Non-food-grade containers often contain additives like phthalates or flame retardants that break down when exposed to sunlight and heat. These chemicals migrate into the water, potentially harming soil health or sensitive plants. For example, barrels previously used to store industrial solvents or dyes often retain hazardous residues in the porous plastic walls that no amount of scrubbing can fully remove.

An important exception involves high-density polyethylene (HDPE) containers marked with a recycling code of 2. While these are generally safer than other plastics, they are only appropriate if they were originally food-grade. Using a container that held non-food chemicals is never safe, regardless of the plastic type, because the risk of long-term chemical leaching remains far too high for home irrigation.

How can the weight of a full rain barrel create structural issues or safety hazards for homeowners?

Concentrated weight creates a high risk of structural failure, particularly when barrels are placed on elevated wooden platforms or soft, uneven soil.

• 450 pounds of pressure can easily buckle a standard deck board if the barrel isn't positioned directly over a structural joist.
• Soil compaction beneath a heavy base often leads to the barrel tilting, which can cause the downspout connection to snap and leak.
• Shear force during a high-wind event can cause a top-heavy, full barrel to tip over, potentially crushing nearby landscaping or injuring pets.
• Foundation settling occurs if water leaks from a base, softening the ground and causing the home's perimeter to shift over time.

What are the limitations of using stored rainwater for indoor household applications?

No, rainwater is generally unsuitable for indoor use because it lacks the filtration and disinfection required to meet potable standards. Even for non-potable indoor tasks like toilet flushing, the plumbing modifications required to integrate a 50-gallon barrel are often cost-prohibitive and violate most residential building codes.

In what ways can the installation of a rain barrel system be cost-prohibitive or inefficient for certain climates?

In arid climates with long dry spells, the high upfront cost of a barrel system rarely pays for itself through water savings.

Compare your local average annual rainfall to these figures to estimate if the initial investment will provide a reasonable return on your time and money.