Visit the Sweetwater LLC blog
Visit the Sweetwater LLC blog
Connect with Jim on LinkedIn

Rainwater Filtration

 This page describes the rainwater filtration systems I sell.


Kitchen Defender under sink filter for rainwater

Kitchen Defender for rainwater
with 5 micron filter, carbon block, and bacteria/virus block filter

Rainwater was once pristine and the very best source of water. Plus rainwater refreshes every water source on the planet: rivers, lakes, reservoirs, oceans, and well water are all replenished by rain. PFAs and PFOAs are now present in rainwater at levels considered unsafe. What this means for you is that your water source contains them too. Rainwater generally contains vaporized mercury and may contain pesticides. 

Rainwater collection can be simple or complicated depending on whether or not you've planned for it before building or are retrofitting an existing structure. I recommend searching Amazon for books on rainwater collection, such as Design for Water.  While this book's information on rainwater collection is very good, it's information on rainwater purification is not.

Rainwater purification has grown more complex due to the spread of pollutants on trade winds that travel all around the planet. Mercury from coal plants in China spreads to the entire Western US riding across the ocean on the trade winds.  When collecting rainwater or spring water plan to purify for bacteria and the presence of mercury and pesticides. Rainwater filtration need not be complex or costly, but treating rainwater must be thorough enough to account for the pollutants likely to be present. Mercury and pesticides are now present even in pristine environments requiring rainwater filtration even in remote locations. Filtering rainwater is similar to what would be done for high quality mountain spring water.

If you're planning to drink the rainwater then my Kitchen Defender for rainwater is perfect for rainwater or spring water.  It will function even in remote areas with no electricity because it relies entirely on mechanical filtration for bacteria and viruses. You will have to use an electric or manual pump (a foot pump like those used on sail boats will work) or gravity to get the water to flow through the system.

Pricing: Kitchen Defender for rainwater: $386 plus shipping

Click here to request specifications and pricing on the Kitchen Defender for Rainwater

KD kit 2020

Kitchen Defender with install kit


To preserve the integrity of the Kitchen Defender from sediment you'll need to use a whole house 5 micron filter ($205).

 Urban Defender and UV light Ohio retouch

Sweetwater's Urban Defender and UV light for rainwater

For whole house rainwater purification you'll need my whole house rainwater system: Sweetwater's Whole House Rainwater Treatment with UV light. Clearly electricity is required for this setup.


Collecting rainwater will be unique to each building site but I've included a sketch and a couple of photos to provide some ideas on the approach.  You'll need to collect rainwater from a rooftop, filter the large debris and the initial wash, then store the water, and then pump it to your rainwater purification system.  Filtering rainwater with a large micron filter is a good idea but treating rainwater should take place after storage because it will be virtually impossible to keep the stored water contaminant free.


rainwater collection, rainwater purification, collecting rainwater


Also available as a pdf: rainwater collection system


Here are some ideas for collecting and purifying rainwater drawn by a rancher in Texas who uses my system:

rainwater collection and diverter valve sketch


collecting rainwater, filtering rainwater, treating rainwater, rainwater collection

The above photo illustrates storage tanks used by a customer in Texas.


collecting rainwater, rainwater collection, filtering rainwaterWater is then piped to the point of use.

The photo on the right illustrates the overflow for the initial dirty water after a rain.

I can also provide whole house solutions including Sweetwater's Whole House Rainwater Treatment with UV light. Click on the link to request specifications and pricing.




Request specifications and pricing on the Kitchen Defender for rainwater

To preserve the integrity of the Kitchen Defender from sediment you'll need to use a whole house 5 micron filter ($205).




If you'd like to discuss your specific project, give me a call.





 "What's in YOUR Water?"

James P McMahon, ecologist - rainwater filter systems
James P McMahon



 To view my experience and credentials:

JPM Biography



I don't take American Express