Rain Barrels

Regulations and How to Begin Collecting Rain Water

This webpage is intended to provide information on the regulations regarding rain barrels, the environmental benefits of using a rain barrel, how to build rain barrel, operation and maintenance of rain barrels, and where to locally find all the necessary equipment to begin collecting rain water. A rain barrel system can come prefabricated or it can be constructed in a do-it-yourself fashion. The differences between these methods, as well as a break down of the do-it-yourself process is included below.

Rain Barrels Regulations

House Bill 16-1005 allows residents of Colorado to now collect up to 110 gallons of rainwater. Guidelines for following House bill 16-1005 are listed below.

House Bill 16-1005

• Legal to collect rainwater from downspout of roof.
• Rain barrel requires a sealable lid.
• Rain barrel must be located above ground.
• Limited to 2 rain barrels with total storage capacity of 110 gallons.
• Collect rainwater from single family residence as a detached house or part of a row of houses.
• 110 gallons per multi-family residence building with 4 or fewer units.
• Collected rainwater can only be used for outdoor purposes on the property it is collected on.

Additional Resources for Regulations on Rain Barrels

CSU Fact Sheet on Rain Collection in Colorado
CDPHE Information on House Bill 16-1005
CDPHE Best Practices in Sustainability for Rain Barrels
CDPHE Rainwater Collection Information Table

The Benefits of Collecting Rain Water

• Reduces runoff pollution in urban waterways.
• Reduces use of treated water to maintain lawn and gardens saving
• Helps reduce erosion due to stormwater runoff.
• Helps control moisture around the foundation of a house.
• Having a 110 gallon rain barrel system could sustain a 7×7 ft. garden, or a 14×14 ft. lawn.

Vegetable Garden
¼ inch per day (3.5 inches/week)
1 inch per water application
Vegetable Garden Irrigation
110 𝑔𝑎𝑙𝑙𝑜𝑛𝑠 ∗ (0.134𝑓𝑡3)/𝑔𝑎𝑙𝑙𝑜𝑛 = 14.7𝑓𝑡 (14.7𝑓𝑡3)/(3.5 𝑖𝑛𝑐ℎ) ∗ (1 𝑖𝑛𝑐ℎ)/(0.08 𝑓𝑡) = 53𝑓𝑡2 = 7ft. * 7ft. garden

Turf Lawn
1-3 inches per week
1 inch water per application
Lawn Watering Fact sheet
110 𝑔𝑎𝑙𝑙𝑜𝑛𝑠 ∗ (0.134𝑓𝑡3)/𝑔𝑎𝑙𝑙𝑜𝑛 = 14.7𝑓𝑡3 (14.7𝑓𝑡3)/(1 𝑖𝑛𝑐ℎ) ∗ (1 𝑖𝑛𝑐ℎ)/(0.08 𝑓𝑡) = 184𝑓𝑡2 = 14ft. * 14ft. lawn

Rain Barrel Installation

This section describes the differences between prefabricated and DIY rain barrel systems, the process of locating the optimal location for the rain barrel, the process of determining how much rainwater could be collected by the rain barrel system, inform and give options for the system components, and provides video tutorials on how to set up a DIY rain barrel. This section should help determine if a DIY or prefabricated rain barrel will be best for your situation.
Do it Yourself vs. Prefabricated


• Cost effective

• Design has more flexibility

• Recycling 55 gallon barrels is more sustainable

• More construction time

• Need access to more tools and parts


• Less set up time

• Less tools required

• Some barrels leak

• More expensive

Site Selection
1. Rain barrel location should be in an area that is close to where the water will be used.
2. The rain barrel will need to be near a downspout.
3. The contributing roof area to the selected downspout should be calculated to know the amount of rainwater that could be collected.
4. The site selection could be different based on watering methods (hose or bucket/pail).

Calculating Contributing Roof Area

• Course measurements (tape measure or by strides)
• Using a geospatial program – eRAMS
• Measuring from roof plans

Below is a graph that shows the required downspout drainage area in square feet to fill either a 55-gallon or 110-gallon system with a 0.25″ precipitation event.

The table below categorizes the size and number of rainfall events on average for the Denver area.

Rain Barrel Components
This section provides information on the components of a rain barrel system and lists options for where to find these components.


• Stores the rainwater (Prefabricated or recycled)

A list of prefabricated barrel options is below.

Enviro World Corporation Rain Barrel, 55 Gallon ~ 90$

• This prefabricated rain barrel system does not come with a diverter, and will need to be purchased separately.

• People have said that this product is easy to set up, a removable lid with a filter is included, but the spigot is not made of metal and the system can leak because of this.

Upcycle 55 Gallon Gray Rain Barrel ~140$

• This system has multiple locations for spigot placement increasing the design flexibility of the system.

• People have stated that this system does not leak (which is an issue for prefabricated barrels) in online reviews.

• The placement of the overflow fitting is angled upward which can result in kinking of the overflow hose.

Good Ideas RW50-KHA Rain Wizard Rain Barrel 50-Gallon ~85$

• This is a cheap option for a prefabricated barrel and online reviews say that the system has lasted without leaking.

• There are two locations for spigot placement on this barrel.

• Some reviews have stated that the holes in the filter are so small that water can splash over in high flow runoff events.

Information on where to purchase 55-gallon recycled barrels is located below.

Colorado Rain Catcher
Fort Collins

Re-purposed Materials

Container Reclaimer

Blue Barrel
Pick up in Lafayette,Louisville, Denver, Colorado Springs


• Diverts water from the downspout to the rain barrel .

• Some diverters have an included downspout filter.

• Some diverters work as an overflow as well.

Fiskars Rain Barrel DiverterPro Kit ~ 35$

• This diverter comes with a downspout filter to remove debris.

• Will work as a diverter and overflow device.

• Some people have said the inside chamber can be leaky, but that this problem is fixable.

Oatey 14209 Mystic Rainwater Collection System ~ 25$

• This diverter works with a 2×3″ downspout.

• Comes with 4′ hose to connect to the rain barrel.

Flex-Drain 85010 Downspout Extension ~ 13$

• This diverter is cost effective and easy to install.

• This diverter will diver all of the rainwater to the rain barrel, but an overflow will need to be connected to the rain barrel if this diverter is used.

Rain Harvesting Pty Downspout First Flush Diverter ~40$

• This diverter stores the first gallon of runoff before diverting the runoff to the barrel which should improve the quality of the water collected.

• People have said this diverter does not have problems leaking, but does require more maintenance than a typical diverter.


• Screened opening for water to flow in and to remove debris.

• Can be created cutting a hole in the top and using 1/8″ screen to cover the hole.

• Can be a prefabricated, but there is room for creativity if on a budget.

• Some systems pipe the rainwater directly from the diverter to the barrel (this method may require a downspout filter to avoid debris entering the rain barrel or clogging diverter).

6″ Double Screened Rain Water Inlet ~ 15$

Go Green Rain Barrel Screen ~ 10$


• Used to attach a hose or fill bucket/pail.

• A bulkhead fitting will be required as well to attach the spigot.

Rain Barrel DIY Spigot Brass Ball Valve and Bulkhead Fitting ~ 20$

• Bulkhead fitting is included, but Teflon tape may be needed to ensure no leaking.

EarthMinded Brass Spigot ~ 15$

• Bulkhead fitting would need to be bought separately.


• Diverts excess rainwater away from the house.

EarthMinded – Rain Barrel Overflow Drain Kit – 20$

• Comes with the required hole saw included.

• The hose has a 1 1/4″ diameter to allow for a high flow rate which will help avoid drainage problems during overflow in heavy rain events.

Downspout Filter

• Downspout filter could be needed if there is debris in the runoff.

• Filters the debris before it enters the rain barrel.

• Will help prevent clogging due to debris.

• Debris build up in the filter will need to be removed periodically.

Leaf Eater Advanced Rain Head ~ 35$

• This downspout filter could be used as an inlet to the rain barrel.

In-Line Downspout Filter – Slim Line ~ 45$

• People have said that this filter looks better than others and is easy to maintain

DIY Downspout Filter

• People have made DIY filters with two 6″ plant pots and an 1/8″ screen in between them. If on a budget a DIY filter may be a more economical solution.


• Elevates rain barrel to allow for a watering can to be filled.

• Can be created using concrete, bricks, or wood.

• It is important to level the ground before installing the stand.

DIY Kits

DIY kits can make the materials collection for setting up a DIY rain barrel easier. Below are a few DIY kit options.

Colorado Rain Catcher DIY kit ~ 40$

• This kit is easy to winterize.

• An overflow would not be required with this kit.

• The system is sealed off to avoid mosquito problems.

• The spigot on this kit is brass which is preferred.

Earth Minded Do-It-Yourself Rain Barrel Kit ~ 35$

• This kit is easy to winterize.

• An overflow would not be required with this kit.

• The system is sealed off to avoid mosquito problems.

• The spigot on this kit is plastic, and a kit with a brass spigot would help avoid leaking issues.

Materials Needed
• Food grade 55 gallon barrel
• Downspout diverter
• ¾” Spigot
• 2 bulkhead fittings
• 1” hose about 6’ long
• Concrete or brick base
• All weather silicone
• Teflon Tape
• Screen for inlet
• Downspout filter (if debris removal is needed)

Tools Needed
• Hole saws (size of the bulkhead fittings)
• Drill
• Jigsaw or reciprocating saw
• Flat head screwdriver
• File
• Tape measure and marker

Other Materials
Other materials may be needed to set up your rain barrel. If extra materials are needed they can be found at hardware, garden supply, pluming supply, and pool supply stores like:

Home Depot

Fort Collins Nursery

Ferguson Plumbing Supplies

High Country Pool and Spas

Below are videos that give step by step instructions to set up your own rain barrel

Rain Barrel Operation and Maintenance

This section will describe operational considerations of rain barrel use which includes mosquito control, algae build up, and steps to winterize. If in search of more information on rain barrel operation and maintenance the links in the additional resources below go into further detail.

Rain Barrel Use

• Best to use within 7 days.

• Empty, clean and dry once a month.

• Disconnect if leaving home for an extended period of time.

• Downspout filter must be cleared of debris periodically.


• Mosquitoes live in water for 3-7 days.

• Mosquito “dunks” available at hardware stores.

• Mosquitoes require oxygen – using several tablespoons of vegetable oil will create a barrier at the water surface.

Algae Build Up

• Frequent use of water should prevent build up of algae.

• If rain barrel is translucent, paint it dark.

• Remove algae with dilute (2%) bleach solution, discharge bleach solution to sewer not plants.


• Rain barrels are used from March-October.

• Frozen water could damage components of rain barrel.

• When done collecting rain for the year empty and dry, store indoors if possible.

• If storing rain barrel outdoors turn the barrel over to avoid moisture build up.

• Add a downspout extension to avoid erosion.

• Some kits come with winterization parts that make the process easier.

Additional Resources for Operation and Maintenance of Rain Barrels

Steps to Winterize a Rain Barrel

Mosquito Control Information

Algae Control in Rain Barrels

Rain Barrel Fact Sheet