The Why, Where and How To of Rainwater Catchment Systems

On today’s podcast I will discuss everything you need to know about building your very own diy rainwater catchment system. From why you should build one, where it should be, to the details of how to build a rainwater capturing setup.

I discuss:

Why you should consider putting in a rainwater catchment system.Laws pertaining to rainwater catchment.Where to install a rainwater catchment system.Options for capturing water.Specific pieces to a catchment system.How to care for and maintain a catchment system.Using the water from your rainwater catchment system.

Why Install a Rainwater Catchment system?

Conserves Water – Having stored rainwater can save a lot on the use of water from a municipal water supply or even your well during dry parts of the year,even more if you set up your system for greywater use.

Possibly Conserves Energy – If your water comes from a well then every time you use a gravity fed rainwater storage system for your water needs you are saving on the use of your well pump which can have significant energy savings.

Water Security – Everything needs water to survive and having hundreds of gallons of stored water on hand for emergencies is never a bad thing.

Where to install a rainwater catchment system.

Rainfall Amount Considerations. – The average roof collects over 600 gallons of water for every inch of rainfall.

Water Needs. – What are you going to be using the collected rainfall for? This will have a direct impact on the location of your system.

Roofing Material. – This can make a difference depending on the purpose of the water. Metal roofs are best but asphalt shingles are fine depending on the water use.

Options for capturing water.

Barrel Collection – Food grade plastic barrels or IBC tanks.

Cistern – Rooftop cisterns, attic cisterns, ground-level and below-ground-level water storage cisterns.

Using Berms and Swales – This is called passive water harvesting and it’s the practice of slowing water down and encouraging it to soak into the ground. With simple land contouring that catch and direct stormwater runoff, rainwater can be used beneficially, encouraging plant growth in landscapes and natural areas, healing erosion cuts, and can even replace the need to irrigate with tap water. 

Ponds – I will defer you to page with information and a video explaining more about using ponds and water features for rainwater storage. –

Specific pieces to a catchment system.

Downspout Diverter – This flushes away leaves and large debris before entering the catchment system. 

Downpipe First Flush Water Diverter – This divertes the first few gallons of rainwater away from the storage tank until the roof is washed clean of dust and fine particles.

Screen/Filter – This captures what’s left of any fine debris that were missed by the diverters maintaining cleaner water in your storage tank.

Collection Tank – This will be the final storage place for your clean rainwater. This can be a large cistern, plastic barrels or IBC tanks.

Overflow Valve – Your collection tank will eventually fill up so it will need to be fitted with an overflow valve which will allow the rainwater to be diverted to the ground once that happens.

How to care for and maintain a catchment system.

Emptying First Flush Barrel or Pipe

Cleaning Screens/Filters

Treatment For or Preventing of Algae – Block sunlight, use hydrogen peroxide,

Freeze Protection – Drain or heat.

Using the water from your rainwater catchment system.

Garden and Landscape Usage.

Grey Water Usage

Using Rainwater For Drinking and Cooking – Must be filtered.

Resources and Product Links:


Rain Harvesting Downpipe First Flush Water Diverter Kit

Downspout Diverter

250 Gallon Rain Harvest Collection Tank

Rain Barrel Quarter Turn Ball Valve Spigot with Bulkhead Fitting

Rain Barrel Connector Kit

Other Links

Basic rainwater collection calculations

Big Berkey Water Filtration System

It is now legal to collect rainwater in Colorado. HB 16-1005 is the bill that was signed May 12, 2016.


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