Collecting roof runoff is legal in most of the US, but each state sets its own rules and a few limit it.

Colorado, for example, allows single-family homes at most two barrels holding 110 gallons combined, for outdoor use only. Utah caps total storage and asks you to register larger systems.

Outside the US, rules vary by country and region, and some places require a permit.

Check with your local water authority before you buy.

Homeowners associations and some cities set rules on where a barrel can sit and what it looks like.

Read yours before installing one in view of the street.

Many water utilities and cities sell discounted barrels or pay rebates on them.

Search your utility's website before paying full price.

02

Safety and water quality

Harvested rainwater is not drinking water. Roofs collect bird droppings, dust and chemicals from roofing materials, so never drink it, cook with it or give it to pets unless a properly designed treatment system has made it safe.
Keep children out: A lid that latches or screws down and cannot be lifted by a child, on every barrel and tank. Even a partly full open container is a drowning risk for small children.
Every opening needs a fine mesh screen. Mosquitoes breed in standing water within about a week, so a torn screen or a gap at the diverter inlet turns your barrel into a breeding site. A larvicide dunk made for mosquito control adds a second layer.
Overflow has to go somewhere safe. Pipe it at least 5 feet from your foundation, onto ground that slopes away from the house, and never toward a neighbor's property.
Edible crops need more care. Water from asphalt shingle, treated wood shake or copper roofs, or roofs with zinc or copper moss strips, is best kept for ornamentals and lawns. If you use roof water on vegetables, water at the soil, not over leaves or fruit, and wash produce well.
A full 55-gallon barrel weighs about 450 pounds. Set it on a firm, level base so it cannot tip or sink.

03

How much water to expect and where the barrel goes

Roof math

Every inch of rain on 1,000 square feet of roof yields about 600 gallons. A single downspout usually drains a quarter to a half of the roof, so even a light shower can fill a 50-gallon barrel.

Pick a downspout near the beds you water most, on ground you can level, with room to route overflow away from the house.

Height is your water pressure.

Raising the barrel 1 to 2 feet on a stand lets a hose fill a watering can or run water downhill to a bed.

Shade helps.

A barrel out of direct afternoon sun grows less algae, and an opaque barrel matters more than a pretty one.

A tall rainwater tank on a brick base beside a timber shed, with an outlet pipe near the bottom — A tank set on a level, solid base

04

Set up your first rain barrel

What you can do in your first month

One working barrel

A barrel on a level stand, fed by a downspout diverter, with overflow piped well away from the house.

A storm log

Note how much rain fell and how full the barrel got, so you learn what your roof actually delivers.

A watered bed or pot collection

Run a hose from the spigot and water your plants for a few weeks on rain alone.

A mosquito-proof barrel

Check the lid screen after each storm and keep a larvicide dunk working inside.

After each storm, take a quick look: lid screen intact, diverter not clogged with leaves, overflow running where you meant it to.
Clean the gutters and the diverter screen in spring and fall; leaves and roof grit are where most clogs and bad smells start.
Replace the mosquito dunk about once a month during the warm season, or as the label directs.
Before the first hard freeze, drain the barrel, leave the spigot open, set the diverter to bypass, and store the barrel upside down or indoors. Ice can split a barrel and crack its fittings.

06

What trips beginners up

Expect slow flow.

Gravity pressure fills a watering can steadily but will not power a sprinkler or a long soaker hose without a pump.

Expect the barrel to fill faster than you think and run dry in a drought.

One barrel tops up beds between storms; it will not carry a garden through a dry month.

Do not convert a used drum unless you know it held food.

A drum that once held chemicals can leach them into your water and soil.

Do not leave water sitting all summer.

Use it, and empty and rinse the barrel if it smells or grows a slick of algae.

07

Where to learn more

Your state's extension service is the best free source for local rules and climate-specific advice, and many run rain barrel workshops. The national resources below cover the basics and the step up to larger tanks.

Three green plastic water tanks, one raised on a steel tower, in a paved brick courtyard — Larger tanks, the step up from barrels

Free guides and the catchment association

08

About this shopping list

The essentials are a barrel with a screened lid and spigot, a diverter that connects it to your downspout, and an overflow hose so excess water lands well away from the house. A stand, mosquito dunks and a short hose turn that into a setup you can actually water from. Buying the barrel ready-made costs more than converting a food-grade drum but saves drilling, sealing and screening it yourself. The optional lines are for later: a linking kit to add a second barrel, a first-flush diverter for cleaner water, and a small pump when gravity is not enough.

Compare the options on each line, then set your tiers and check out from the barrel list. Clicking a card selects it there, and clicking the selected card again takes that line out. The essentials and the recommended lines start in the kit; the three optional upgrades stay out until you add them.

Rain barrel with screened lid and spigot

Essential · Core equipment

This is where the water is stored. A barrel built for the job comes with a fine mesh screen over the inlet, a spigot near the bottom for a hose and an overflow port near the top.

budget

RTS Home Accents 50-Gallon Rain Water Collection Barrel with Brass Spigot, Oak Color

4.4(759)

$99.00

Rainwater Harvesting

Check the rules where you live first

Safety and water quality

How much water to expect and where the barrel goes

Set up your first rain barrel

Keeping it running through the year

What trips beginners up

Where to learn more

About this shopping list

Set up the barrel

Rain barrel with screened lid and spigot

Downspout diverter kit

Overflow hose or downspout extension

Rain barrel stand

Mosquito larvicide dunks

Short garden hose

Rain barrel linking kit

First flush diverter

Rain barrel pump